# The role of "once" in "once every X days"



## meijin

Hi, I'm wondering if the addition of "once" makes the phrase "every X days" mean any different. I mean, why do you add it when you add it? 

For example, if you see your doctor "*once* every three days", does it mean any different from seeing your doctor just "every three days"?
Can "*once* every three days" mean pattern 2 below? (I'm 100% sure "every three days" means pattern 1.)


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## lingobingo

Your interpretation is right. Unless otherwise specified, it simply means at 3-day intervals. There would normally be no need to add “once” – unless there was some reason to make it clear that twice or more was not meant (for example, in dosage instructions for a medication).


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## meijin

Thanks lingobingo. Am I right in thinking that "once every three days" is the only natural way to describe pattern 2?


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## lingobingo

If you say either every 3 days or once every 3 days, the natural assumption will be a regular pattern, even if that’s not stated. If an irregular pattern is meant, no one will know that unless you spell it out.


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## meijin

lingobingo said:


> If you say either every 3 days or once every 3 days, the natural assumption will be a regular pattern, even if that’s not stated.


If I said "I go to see the doctor *every three days*" and later showed you my calendar showing patter 2 above, would you say, "That's NOT every three days"? If so, is it better to say "*once* every three days"?



lingobingo said:


> If an irregular pattern is meant, no one will know that unless you spell it out.


How would you spell that out in English if you didn't have the calendar with you? Would you write down the numbers? Or would you explain like "_I go to the doctor on one of the first three days, then go there again on one of the following three days, then..."?_


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## JulianStuart

meijin said:


> Thanks lingobingo. Am I right in thinking that "once every three days" is the only natural way to describe pattern 2?


Pattern 2 is not described by "once every three days" or "every three days".  It could be described as "five times in 15 days in an irregular fashion" or similar.  As Lingo says, "every interval" implies a regularly spaced pattern.  In fact, pattern 2 isn't really even a pattern  If pattern 2 happens every 15 days (  ) then you would have to spell it out: "I go on days 1,5, 7, 12 and 13 in each 15 day cycle" - there's no shorter way to specify it


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## lingobingo

meijin said:


> If I said "I go to see the doctor *every three days*" and later showed you my calendar showing patter 2 above, would you say, "That's NOT every three days"? If so, is it better to say "*once* every three days"?


It’s every 3 days whether what’s meant is the same time every day or a different time every day. They are two separate things. Adding *once* makes no difference apart from making it clear that it’s no more than once a day.


meijin said:


> How would you spell that out in English if you didn't have the calendar with you? Would you write down the numbers? Or would you explain like "_I go to the doctor on one of the first three days, then go there again on one of the following three days, then..."?_


If you needed to explain an irregular pattern, you would do so in whatever way was most appropriate to the situation.


cross-posted


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## meijin

JulianStuart said:


> In fact, pattern 2 isn't really even a pattern If pattern 2 happens every 15 days (  ) then you would have to spell it out: "I go on days 1,5, 7, 12 and 13 in each 15 day cycle" - there's no shorter way to specify it





lingobingo said:


> If you needed to explain an irregular pattern, you would do so in whatever way was most appropriate to the situation.


Thanks both. Maybe Julian knows this, but in Japanese there's a very commonly used short expression that describes pattern 2, and we consider it a pattern (although many of us don't wonder what that short expression really means). So you know why I've been so particular about the difference between the two expressions above.


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## lingobingo

On one occasion when I had to call out an ambulance for my little old mum, her heartbeat was not quite as it should have been. But the paramedic said don’t worry, it’s regularly irregular! I guess that’s the case here too.


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## JulianStuart

meijin said:


> Thanks both. Maybe Julian knows this, but in Japanese there's a very commonly used short expression that describes pattern 2, and we consider it a pattern (although many of us don't wonder what that short expression really means). So you know why I've been so particular about the difference between the two expressions above.


The irregular one would normally only be called a "pattern" when it is "repeated (once) every X days" - this uses the definition of pattern referring to the distinction bewteen a pattern of events and a set of randomly spaced events.


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## meijin

JulianStuart said:


> The irregular one would normally only be called a "pattern" when it is "repeated (once) every X days"


Yes, but both patterns 1 and 2 above are repeated "(once) every three days", aren't they? So pattern 2 is also a pattern, isn't it?


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## JulianStuart

meijin said:


> Yes, but both patterns 1 and 2 above are repeated "(once) every three days", aren't they? So pattern 2 is also a pattern, isn't it?



Pattern 2 cannot be repeated every three days because the sequence is 15 days long.  There are two intervals (one of 3 days and one of 4 days) where nothing happens.  It is "on average" that there are 5 events in 15 days (and 15/5 = 3) but that is NOT the meaning of "once every three days". "Pattern 2" cannot be described that way.


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## meijin

I'm sure you consider "once a week" a pattern (or maybe I misunderstand the meaning of the word 'pattern'? ), so I suppose one needs to describe pattern 2 as "once a/every three-day period" to make it a pattern although it is unidiomatic?


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## JulianStuart

meijin said:


> I'm sure you consider "once a week" a pattern (or maybe I misunderstand the meaning of the word 'pattern'? ), so I suppose one needs to describe pattern 2 as "once a/every three-day period" to make it a pattern although it is unidiomatic?


Yes, once a week is a pattern.  The events in what you call pattern 2 are not regular so you *cannot, cannot, cannot* say "every three days" or "every three day period" - if you insist on using "three days" in your expression you MUST use the term "on average".  The irregular sequence in "pattern 2" only becomes a pattern if it is itself repeated every 15 or more days.

You were correct in the  OP "I'm 100% sure "every three days" means pattern 1.)"


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## meijin

JulianStuart said:


> Yes, once a week is a pattern. The events in what you call pattern 2 are not regular so you *cannot, cannot, cannot* say "every three days" or "every three day period"


By any chance, does the "once" in "once a week" have to happen on the same day of the week in English? (But that would be "weekly" in my opinion.) In Japanese, it's not. If I go to a gym on Wednesday this week, Monday next week, Friday the week after next, and so forth, it's still "once a week" in Japanese. It's the same as pattern 2 above. The only difference is whether it's a seven-day period or three-day period. Maybe I'm missing something very important? I'm sorry, I still don't understand.


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## JulianStuart

Every three days means: day 1 day 4 day 7 etc (i.e.wherere each interval is, well three days!).  Day1, day 2 and day 7 is NOT every three days.  "Once a week" does not require it to be the same day each week (although it often is), while (once) every seven days does require the gaps be 7 days.  If it is always the same day, and that is _important_ to the communication, one could either say every seven days or e.g., every Tuesday.

You were correct in the  OP "I'm 100% sure "every three days" means pattern 1.)"
Just to re-re-iterate, that's all it ever means.

Perhaps there's an expression in Japanese that means what you want but, one more time, in Engish you must add "on average" if the interval between events is a variable.


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## meijin

JulianStuart said:


> Every three days means: day 1 day 4 day 7 etc (i.e.wherere each interval is, well three days!). Day1, day 2 and day 7 is NOT every three days.


Well, I don't blame you, Julian, but you've clearly misunderstood my replies (or I've misunderstood your replies ). I have ABSOLUTELY no problem with "every three days". And I learned from lingobingo's replies that "*once* every three days" does NOT mean what I thought it might mean. What I _am_ wondering is just this. Aren't *"once every 7-day-long period* (*=once every week*, if the 7-day-long period begins from Sunday or Monday)*"* and *"once every 3-day-long period"* both a _pattern_? If you call only the former a pattern, is that because there's no word like "week" for the latter?


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## JulianStuart

The "pattern" definition I tried to explain in #10 is where the following numbers form a pattern (or are formed not at random).  If you ask people "Do you see the pattern in the number series below?" they will say yes.
1 1 2 3 5 8 13 21 ...(Fibonacci)
2 4 6 8 10 12 ...
2 4 8 16 32 64 ...
3 9 27 81 ...
If you ask them about the series in your "pattern 2" they will be puzzled and probably say "No, they're some sort of random progression - there's no pattern to the series."
1, 5, 7, 12 and 13

You had said 





meijin said:


> *to describe pattern 2 as "once a/every three-day period" *to make it a pattern although it is unidiomatic?


 and that was what I responded to - you cannot do that to describe "pattern 2"


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## meijin

Well, then why did you call once a week a pattern when the intervals between the days are random?

(If non-native speakers are reading this thread, please help.  You surely know what I mean, don't you? You don't have a commonly used short expression for pattern 2 in your country?)


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## JulianStuart

Once a week is a pattern (this definition meaning regular in some way), once every three days is a pattern,

Every three days: Day 1, day 4, day 7 (pattern = each number is three greater than the previous)
Every week/7 days: day 1, day 8, day 15 (pattern = each number is seven greater than the previous)
1 1 2 3 5 8 13 21 ...(Fibonacci) (pattern =each number is the sum of the previous two)
2 4 6 8 10 12 ...(pattern = each number is two greater than the previous)
2 4 8 16 32 64 ... (pattern = each number is two times the previous number)
3 9 27 81 ... (pattern = each number is three times the previous number)
are all "patterns"

Your schedule/scheme 2=   1, 5, 7, 12 and 13 (pattern is ???

With another definition of pattern, any arrangement of anything can form a pattern - this meaning does not sarry the repetition/regularity meaning.  Pattern 2 could come under such a definition but it cannot be described as (regularly) every three days - you have tried that several times and that is what I've responded to.


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## meijin

(This will probably be my final attempt in this thread...)

_If_ there were only 3 days in a week (Mon-Wed) and if May 1 in the calendar above were Monday, would you call pattern 2 a pattern?


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## JulianStuart

meijin said:


> (This will probably be my final attempt in this thread...)
> 
> _If_ there were only 3 days in a week (Mon-Wed) and if May 1 in the calendar above were Monday, would you call pattern 2 a pattern?


Only in the (rather useless) sense of "an arrangement": there is no regularity to the interval between events.  It is a _schedule of events_ (the length of the week and the date have no bearing on this issue).  The intervals between events are 3 days, 1 day, 4 days and 0 days.  It's irregular, seemingly random.  Are we now discussing the meaning of "pattern" or your attempt to characterize "pattern 2" as "every three days"???????


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## meijin

Julian, I had hoped I wouldn't have to do this. But please see the following revised calendars.






I think a simple YES or NO answer will be very helpful in this case. There are four "Once a week"s in the calendars. Are *2a* and *2b* also a "*pattern*" as long as you describe them as "*once a week*"?

Note that 2a is exactly the same as pattern 2 in the original post.


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## JulianStuart

I'll ignore the 3-day week examples (they don't change anything under disucssion) and remind you of _my earlier comment regarding 1b and 2b_ (they differ only in regularity, not _average_ frequency), in case you missed it  As I said  anything can be a pattern so let's leave the discussions about the various possible meanings of) that word out of this - it was not an important part of the OP.


JulianStuart said:


> "Once a week" does not require it to be the same day each week (although it often/usually is), while (once) every seven days does require the gaps be 7 days.  If it is always the same day, and that is _important_ to the communication, one could either say every seven days or e.g., every Tuesday.


"I try to get to the gym once a week" is the kind of statement that adds imprecision enough that you might miss one week completely and that the days you _are_ able to go may well not be the same day every week.  If you want precision, you need context.


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## meijin

I give up with the following conclusion:

If there were a word called 'threenight' which means three nights (just like the word 'fortnight' that means fourteen nights), you'd say "I go to see the doctor once a theenight" or "I go to see the doctor once every threenight". Simple as that.


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## JulianStuart

I dunno what all the fuss was about, meijin-san.  Your statement does not make it clear whether you intend the meaning to be that the visits are every three days or (irregularly spaced but on average) once in each three day period (1a and 2a in #24): Post #2 made it clear that whether we talk about weeks, months, fortnights etc,  the use of "once" does not make that distinction clear.If it's somewhat irregular we might well say "I go about every three days".

"Once a week" does not require it to be the same day each week (although it often/usually is), while (once) every seven days does require the gaps be 7 days. * If it is always the same day, and that is important to the communication, one could either say every seven days or e.g., every Tuesday.*


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## meijin

To be honest, I don't know what's wrong with my explanations. I can't explain any better so I had to give up. It just goes to show that something super easy to understand in one language is super difficult to understand in another. 

I only wanted to know how to describe pattern #2 in the example in the original post. If that's not a "pattern", then it should be a "rule". There's no "average" thing there. The visit ALWAYS happens once in each three day period. Sadly, in English there's no short and accurate way to describe that frequency. In Japanese, we say like "once in three days".


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## JulianStuart

It's the ambguity in English that must be resolved with additional words - or more specific wording.  I presume that in your version "once in three days" could be either every third day or any irregular version that has one event in any given three day period (which therefore also could include _more than once in any given three day period_ (see 2a in #24, or the "three day period of 11,12 ad 13 May" in the OP - it happens twice  ).  So in your version it is also ambiguous: both regular and irregular (1 and 2) in OP) are covered by the phrase?


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## meijin

Yes, you're right about that and I'm aware of it. The thing is, in Japanese we have another phrase that clearly means the regular intervals, so when the intervals are irregular, it's more likely to use the "once in three days" phrase. But there's no English equivalent for this. "Every three days" and "Once every three days" will both be interpreted as pattern 1 in the original post.


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## DonnyB

I apologize in advance if someone's already suggested this and it's been rejected, but I'd refer to the original "pattern 2" as "once *in* every three days".

So, in every consecutive three day period, you go to the doctor once, but not at regular intervals as in pattern 1.

Does that make sense?


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## meijin

Wow, is that a natural expression, Donny? Why has nobody suggested that??


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## JulianStuart

meijin said:


> "Every three days" and "Once every three days" will *LIKELY* both be interpreted as pattern 1 in the original post.


 In the complete absence of context, it is LIKELY to be interpreted that way but, once more with feeling and understanding 


JulianStuart said:


> "*Once a week" does not require it to be the same day* each week (although it often is)*, while (once) every seven days does _require the gaps be 7 days_.  If it is always the same day, and that is _important_ to the communication, one could either say every seven days or e.g., every Tuesday.


 You can substitute month threeday, year, whatever named time interval in my bold text and it is still true.  "Take one every three days" from a doctor is pretty unambiguous.  "Take one in every three-day period" is not something we would expect a doctor to say.

*The gym example above  contains additional wording/context to intirduce the possibiity of irregularity.


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## lingobingo

meijin said:


> I only wanted to know how to describe pattern #2 in the example in the original post. If that's not a "pattern", then it should be a "rule". There's no "average" thing there. The visit ALWAYS happens once in each three day period. Sadly, in English there's no short and accurate way to describe that *frequency*. In Japanese, we say like "once in three days".


Without reading everything in this thread (life’s too short!), I would just point out that *frequency*, in its general sense, means the number of times something happens within a specified period — for example, once every three days. (Adding “in” makes no difference whatsoever to this meaning!) That’s all it means. In every consecutive 3-day period, this will happen once.

There is no single word the means a regular or irregular pattern of occurrences within that period.


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## meijin

JulianStuart said:


> In the complete absence of context, it is LIKELY to be interpreted that way but, once more with feeling and understanding


I really don't understand it. I don't know why you highlighted the first part of the first sentence below. I'd highlight the second part, as follows:


JulianStuart said:


> "Once a week" does not require it to be the same day each week (although it often is), while* (once) every seven days does require the gaps be 7 days.* If it is always the same day, and that is _important_ to the communication, one could either say every seven days or e.g., every Tuesday.







lingobingo said:


> I would just point out that *frequency*,


Sorry if that was the wrong word. I wondered about it but just kept typing. I've been awake all through the night so I suppose there are areas in my expressions that aren't quite right. 



lingobingo said:


> (Adding “in” makes no difference whatsoever to this meaning!)


Do you agree with the *"(once) every seven days does require the gaps be 7 days"* part of Julian's explanation? I'm really really confused...


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## JulianStuart

I don't think we will get to clarity about general definitions in the absence of anything guiding the resolution of the ambiguity (which is technically always there but usually not.  The moon is full (once) every 28 days. Full moons are 28 days apart.  Take a pill once every 28 days. In the strictly irregular (once in a time period) version, there is always the possibiity of twice in that same period - for some sitautions that might be a bad thing.

Let's close this loop. In the OP the question was "Does inserting "once" into the phrase help resolve the ambiguity because it has a different meaning?"  I don't think so.


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## meijin

Well, I'll be back in several hours, but if my tired brain understood your posts so far correctly, it seem lingobingo thinks "(once) every three days" can mean either pattern 1 or 2, Donny thinks "(once) every three days" means only pattern 1 and he'd say "once *in *every three days" to describe pattern 2, and I'm not sure at all on which of the two sides Julian is.


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## lingobingo

*Once every 7 days* (or any set time period) means *one time only within each 7-day period*. Even though that does not really imply always at the same time within that period, it would be reasonable to infer that since it’s by far the most likely scenario.

Therefore, if you wanted to make it clear that something else was the case, you would have to spell that out in detail. All of which is basically what I said back in #4 (and #7).


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## meijin

Well, I hope my current understanding below is correct. (I use 2-day periods this time)

*"every other day" "every second day":*
These expressions will always be interpreted as 1, 3, 5, 7, 9... (if you start on day 1), and will be regarded as wrong if it was actually 1, 4, 5, 8, 9....

*"(once) every two days" "Once in every two days":*
These expressions will most likely be interpreted as 1, 3, 5, 7, 9..., but will NOT be regarded as wrong when it was actually 1, 4, 5, 8, 9.... 

*"once (in) every 2-day period" "once a 2-day period"*
These expressions will most likely be interpreted as a pattern like 1, 4, 5, 8, 9.... (or won't make sense at all), but it's an awkward way of explaining it or it's not correct English, so you are more likely to say *"about three days a week"*. 

Have I finally understood and explained it well?


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## lingobingo

I may have got this entirely wrong, but I see it like this…


meijin said:


> Have I finally understood and explained it well?


In short, no. You can safely delete all the misguided conjecture you’ve written in red (and scrap “once a 2-day period”, which is unidiomatic).


We’re talking about two very different things here:

• the frequency of a particular occurrence — that is, how many times something happens during each of a consecutive series of specified time periods

• the times at which individual occurrences take place within that frequency — which may form a regular pattern, or may be irregular or even random​
There is no way of explaining both of these in a single word or phrase.


In summary, the scenarios you’ve outlined in red bear no relation to the terms you’ve highlighted in bold/green. And any assumption on the part of a listener/reader as to the regularity or otherwise of the occurrences in question would be based purely on _perceived_ likelihood.


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## meijin

I think it would be helpful if you could tell me how _you_ would interpret each phrase when you heard it. For example...



meijin said:


> *"every other day" "every second day":*
> These expressions will always be interpreted as 1, 3, 5, 7, 9... (if you start on day 1), and will be regarded as wrong if it was actually 1, 4, 5, 8, 9....


Do you agree with this? If not, why?



meijin said:


> *"(once) every two days" "Once in every two days":*
> These expressions will most likely be interpreted as 1, 3, 5, 7, 9..., but will NOT be regarded as wrong when it was actually 1, 4, 5, 8, 9....


How would you interpret it if I said "I jog every two days" to you? Would you think I jog like "1, 3, 5, 7, 9..." or would you think I jog "once every 2-day period"?



lingobingo said:


> (and scrap “once a 2-day period”, which is unidiomatic)


I know this. That's why I said "(or won't make sense at all)".


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## lingobingo

every other day = on alternate days (a regular pattern)

If you said “I jog every two days” I would take that to mean you do so on alternate days.


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## meijin

Exactly. And that's what the first and second sections of my summary in post #38 are saying. Which means the only point we disagree is the third one. So I really don't know why you had to answer "No". (It seems you should have answered "Mostly correct".)

Anyway, I'm not saying that "once in every 2-day period" and "about three days a week" are the same thing. I meant you'd probably answer the latter because it's more natural. But would you actually use the former expression IF you were asked to be very accurate?

Doctor: So, do you take the medicine every day or every other day?
You: Once in every 2-day period.

Finally, I've just found a site where two English teachers (at least one of them is Japanese) say *"once in two days"* means the same as "once every two days". I think it's wrong. "Once in two days" is grammatically correct, but native speakers wouldn't say it, right?


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## lingobingo

Once in every two days is ambiguous. It implies: at an unspecified time during _either_ of the two days that make up each consecutive pair of days. A most odd scenario.


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## meijin

Is that a reply to my last post where I used "once in two days" (not "once in every two days") or are you referring to the the expression Donny suggested ("once in every three days")?


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## JulianStuart

lingobingo said:


> Once in every two days is ambiguous. It implies: at an unspecified time during _either_ of the two days that make up each consecutive pair of days. *A most odd scenario*.


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## lingobingo

meijin said:


> Is that a reply to my last post where I used "once in two days" (not "once in every two days") or are you referring to the the expression Donny suggested ("once in every three days")?


Wow. I’ve lost the thread of your confusion over all this. 

once in two days = once in every two days / once in three days = once in every three days

The addition of “every” simply confirms that a regular pattern is meant, which is what would be assumed anyway.

But the addition of “in” has already muddied the waters/introduced ambiguity, as explained in #43.


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## meijin

OK, so I have only two questions to end this thread.

1. If I said to you "I jog *every three days*", you'd assume I jog like pattern *1* in the original post. How about if I said "I jog *once in three days*"? Would you also assume pattern *1*?

2. What expression would you use in post #42 when answering that doctor's question, if you think *"Once in every 2-day period"* is unidiomatic?


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## JulianStuart

meijin said:


> If I said to you "I jog *every three days*", you'd assume I jog like pattern *1* in the original post. How about if I said "I jog *once in three days*"? Would you also assume pattern *1*?


 As we have said a few times, in the absence of any hints, the more common situation of days 1,4,7,10 etc is the one that would likely be assumed.  I think if someone said "Once in three days" I woud ask for clarification of the unusual phrase which might itself be a hint.  If they were unabe to jog on a regular schedule, they might well answer with that information "I jog irregularly but about every three days or so" - that could well be enough to make someone think of "pattern 2" in the OP.



meijin said:


> 2. What expression would you use in post #42 when answering that doctor's question, if you think *"Once in every 2-day period"* is unidiomatic?


 "Every other day" is by far most likely what the doctor wants and it is also unambiguous.  A drug or treatment that could happen on _consecutive_ days 2 and 3 (because the first is in the "2-day period" of days 1and 2 and the second in the "2-day period" of days 3 and 4) and then again in day 5 with a gap of two days is highly unlikely to be the intended dosage schedule.


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## meijin

JulianStuart said:


> I think if someone said "Once in three days" I woud ask for clarification of the unusual phrase which might itself be a hint.


This statement is very important/helpful. So, "once in three days" is not unidiomatic but unusual, and it implies that the speaker jogs _irregularly _because otherwise he would have said "I jog every three days". 



JulianStuart said:


> "Every other day" is by far most likely what the doctor wants and it is also unambiguous. A drug or treatment that could happen on _consecutive_ days 2 and 3 (because the first is in the "2-day period" of days 1and 2 and the second in the "2-day period" of days 3 and 4) and then again in day 5 with a gap of two days is highly unlikely to be the intended dosage schedule.


I know what you mean, but let's say you didn't follow the doctor's advice and he's asking you if you've really been taking the medicine every other day.

Doctor: Have you really been taking the medicine every other day?
You: Of course, I've been taking it *once in (every) two days.* (Here, you are trying to make it ambiguous. You didn't take it every other day. ) 

I'm really sorry to tell you that I actually have one, final question. Today I saw a website where a teacher or a dictionary said *"once two days"*,* "once three days"*, etc. are also correct. Really?


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## heypresto

Was it a teacher, or a dictionary? Either way they are talking nonsense.


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## JulianStuart

meijin said:


> This statement is very important/helpful. So, "once in three days" is not unidiomatic but unusual, and it implies that the speaker jogs _irregularly _because otherwise he would have said "I jog every three days".
> 
> 
> I know what you mean, but let's say you didn't follow the doctor's advice and he's asking you if you've really been taking the medicine every other day.
> 
> Doctor: Have you really been taking the medicine every other day?
> You: Of course, I've been taking it *once in (every) two days.* (Here, you are trying to make it ambiguous. You didn't take it every other day. )
> 
> I'm really sorry to tell you that I actually have one, final question. Today I saw a website where a teacher or a dictionary said *"once two days"*,* "once three days"*, etc. are also correct. Really?


a) I would ask for the clarification because it was not, well, clear, not because I thought it implied something specific.

b) How did we get to such a contrived context where you are asking about phrasing required to mislead the doctor who is trying to take care of us?   Your attempt still fails - the "in" is unidiomatic and unusual - if you really are cavalier about the health consquences, you could say "I took 4 doses in 8 days" 

c) agreed with hp - nonsense.


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## meijin

JulianStuart said:


> a) I would ask for the clarification because it was not, well, clear, not because I thought it implied something specific.


Well, but if you really think about it, you'd say "I jog every three days" if you actually jogged on day 1, 4, 7, 10 and so forth. There must be a reason for someone to say "once in three days" instead of  "every three days". The only possible reason I can think of is that they didn't jog with the same intervals.



JulianStuart said:


> b) How did we get to such a contrived context where you are asking about phrasing required to mislead the doctor who is trying to take care of us?


I can see why it's a contrived context in the US, but it's actually not uncommon in Japan. For example, let's say a son is very concerned about his father's health and advise that he should go to see the doctor. The dad thinks he's okay but goes to the doctor because the son really wants him to go. The doctor says that he should take this particular medicine every other day. The dad doesn't really like to take it, but agrees because it will reassure his son, at least for a while. He tries to take the medicine every other day but sometimes realizes that he forgot to take it yesterday, so he takes it now. He goes back to the doctor a week later and the doctor asks "Have you been taking the medicine every other day as I instructed?" The dad answers, "Of course, I've been taking it once in (every) two days". 



JulianStuart said:


> you could say "I took 4 doses in 8 days"


This won't be good for him because it will give the doctor a chance to think "Oh no, maybe he forgot to take the medicine during the first four days and then took it four days in a row". 
"Once in two days", although unidiomatic, would mean that he didn't forget to take it two days in a row. 



JulianStuart said:


> the "in" is unidiomatic and unusual





heypresto said:


> Was it a teacher, or a dictionary? Either way they are talking nonsense.





JulianStuart said:


> c) agreed with hp - nonsense.


Very good. Those are the answers I wanted. So below shows my latest summary.

*once three days *- nonsense
*once in (every) three days *- unidiomatic and ambiguous
*once every three days *- idiomatic but the intervals may not (always) be the same
*once every third day *- idiomatic and the intervals are always the same


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## Myridon

meijin said:


> I can see why it's a contrived context in the US, but it's actually not uncommon in Japan. For example, let's say a son is very concerned about his father's health and advise that he should go to see the doctor. The dad thinks he's okay but goes to the doctor because the son really wants him to go. The doctor says that he should take this particular medicine every other day. The dad doesn't really like to take it, but agrees because it will reassure his son, at least for a while. He tries to take the medicine every other day but sometimes realizes that he forgot to take it yesterday, so he takes it now. He goes back to the doctor a week later and the doctor asks "Have you been taking the medicine every other day as I instructed?" The dad answers, "Of course, I've been taking it once in (every) two days".


What is "not uncommon in Japan"? He was supposed to take it on days 1, 3, 5, and 7, but he took it on days 1, 4 and 7 (every three days).  He tells a lie. Are you saying that being a liar is not uncommon in Japan so you want us to teach you how to tell  lies in English?


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## meijin

Myridon said:


> Are you saying that being a liar is not uncommon in Japan


Being a liar as a patient is not uncommon in Japan. There are many people who don't really trust their doctors. (This isn't surprising, because some doctors are really idiots who keep saying things like you should avoid eating eggs because they are high in cholesterol.)



Myridon said:


> so you want us to teach you how to tell lies in English?


No, lying means to answer "I've been taking it every other day" when he actually forgot to take it two days in a row, which he never did.


Edit: The conclusion part of this post was incorrect, so I deleted it.


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## Myridon

meijin said:


> No, lying means to answer "I've been taking it every other day" when he actually forgot to take it two days in a row, which he never did.





meijin said:


> He tries to take the medicine every other day but sometimes realizes that he forgot to take it yesterday, so he takes it now. He goes back to the doctor a week later and the doctor asks "Have you been taking the medicine every other day as I instructed?" The dad answers, "Of course, I've been taking it once in (every) two days".


He took it on Monday.  He was supposed to take it on Wednesday but he for got and took it on Thursday.  He didn't take it for two days in a row (He didn't take it on Tuesday or Wednesday).  He took it on the first day and the fourth day, not the first day and the third day.  He skipped two days.  There was a two day period in which he took no medicine.


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## meijin

Myridon said:


> He didn't take it for two days in a row (He didn't take it on Tuesday or Wednesday).


He didn't *forget *to take it for two days in a row. That's what I said.


Also, I've just realized that I didn't need to use the unidiomatic expression "once in two days" at all in the doctor vs. patient example. The revised version below works perfectly, in my opinion.

Doctor: Have you been taking the medicine *every other day *as I instructed? 
Patient: Of course, I've been taking it* every two days*.

The doctor clearly asked if the patient had been taking the medicine regularly (on day 1, 3, 5, and 7). The patient used the idiomatic expression "every two days" because he knew the doctor, or anyone else really, would interpret it as day 1, 3, 5, and 7.

What the patient actually did was taking it on day 1, 4, 5, and 8 (he forgot to take it on the 3rd and 7th days). Technically, "every two days" isn't a lie in this case, if it means the same as "*once *every two days".


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## JulianStuart

meijin said:


> What the patient actually did was taking it on day 1, 4, 5, and 8 (he forgot to take it on the 3rd and 7th days). Technically, "every two days" isn't a lie in this case, *if it means the same as* "*once *every two days".


Something about a dead horse. 
In English, in this context, that is* not *a correct "if" .
I'm outta here


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## meijin

From a learner's point of view I must say that it would be more helpful if you could answer like "That one doesn't work, but this one works." Your answer doesn't clearly tell me which of the two expressions works. Sorry.


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## Myridon

meijin said:


> if it means the same as "*once *every two days".


Logically true: If 1 is equal to 2, then horses can fly. 
If the premise is false, the statement is true no matter what the conclusion is.

If "whenever I remember it" means "once every two days", then it is not a lie to say "I take the medicine once every two days."


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## Forero

meijin said:


> Hi, I'm wondering if the addition of "once" makes the phrase "every X days" mean any different. I mean, why do you add it when you add it?
> 
> For example, if you see your doctor "*once* every three days", does it mean any different from seeing your doctor just "every three days"?
> Can "*once* every three days" mean pattern 2 below? (I'm 100% sure "every three days" means pattern 1.)


Adding "once" does not change the meaning of "every three days".

Adding "once in" can be looked at either way.

"One day in every three" is a better description of pattern 2, but I think "one day out of every three" is even better, and "one day of every three, your choice" would more clearly allow irregular spacing as in pattern 2.


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## heypresto

If he had taken the medicine on day 1, 4, 5, and 8, he would be lying if he told the doctor he had taken it 'every two days'.


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## meijin

Thank you both. I couldn't tell this from other posters' replies, so help me. Do "I've taken it once every two days" and "I've taken it every two days" ALWAYS mean EXACTLY the same as "I've taken it every other day"?


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## meijin

Forero said:


> Adding "once in" can be looked at either way.


But I was told that this is unidiomatic and unusual. 



Forero said:


> "One day in every three" is a better description of pattern 2, but I think "one day out of every three" is even better, and "one day of every three, your choice" would more clearly allow irregular spacing as in pattern 2.


Thanks for these suggestions. I'll think about them tomorrow.


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## Forero

meijin said:


> Thank you both. I couldn't tell this from other posters' replies, so help me. Do "I've taken it once every two days" and "I've taken it every two days" ALWAYS mean EXACTLY the same as "I've taken it every other day"?


Yes, unless you explain otherwise. Even if you do, they still might not fit your context.


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## meijin

Forero said:


> Even if you do, they still might not fit your context.


The "pattern 2" in the original post means "every three days" or "once every three days" to me. Do you mean that even if I showed someone that calendar and said "I've been seeing the doctor (once) every three days. Please see this calendar.", he or she might say "No, that's not (once) every three days"?


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## meijin

Forero said:


> but I think "one day out of every three" is even better, and "one day of every three, your choice" would more clearly allow irregular spacing as in pattern 2.


I think "one day out of every three" is very good. If other native speakers find this expression idiomatic, then I'm going to use it and the thread will be over. 
The problem of this thread is that there has been no expression everyone approved of.

I don't know what "one day of every three, your choice" means. I'll think about it tomorrow.


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## JulianStuart

meijin said:


> I think "one day out of every three" is very good. If other native speakers find this expression idiomatic, then I'm going to use it and the thread will be over.
> The problem of this thread is that there has been no expression everyone approved of.
> 
> I don't know what "one day of every three, your choice" means. I'll think about it tomorrow.


Just remember that in pattern two, there is a block of three days and a block of four days where no events happen. This is very unlikely to be appreciated (in any of these expressions) by any listeners unless further explanation is provided.


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## meijin

I know this thread has been frustrating to many but you can imagine it's been frustrating to me as well. 
You can see why it's been so difficult for me to understand, by comparing the following two expressions.

1. once every three days
2. once every third day

I now really wonder why you would say #1 when there's an expression that is 100% unambiguous (#2.)
If I go to a shop and say "I want the third one, please", it will not mean the same as "I want three of those, please."

When "*in*" is added to #1, it's clear at least to me what it means, but unfortunately it has been marked as unidiomatic and unusual. I suppose "unidiomatic and unusual" means like this.

You: So you practice yoga. How often do you do it?
Woman You've Just Met: Once *in* every three days.
You: (Which non-English-speaking country is she from?)

Anyway, it's really surprising that there's no short, idiomatic expression in English starting with "once" that describes "pattern 2" in the original post.


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## JulianStuart

Because “pattern” 2 is both irregular and rare


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## meijin

But as I said there IS a commonly used idiomatic expression in Japanese to mean pattern 2. The important point here is that you, as a speaker, have this "I'm going to do it once in every 3-day period" rule in your mind. This means that even if you forgot to do it on day 5, you can do it on day 6 and you didn't break the rule. If you forgot to do it on day 6 as well, then you broke the rule/pattern. 

Maybe pattern 2 in the original post was a little too extreme and that's why it seemed _rare_. If someone practiced yoga on day 1, 3, 5, 8, 9, 11, 13, 15, 16..., it wouldn't look very irregular. Describing this as "once every other day" or "once every second day" would be a lie. Is describing it as "once every two days" also a lie? ("Yes", according to the previous posts.)


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## JulianStuart

meijin said:


> But as I said there IS a commonly used idiomatic expression in Japanese to mean pattern 2. The important point here is that you, as a speaker, have this "I'm going to do it once in every 3-day period" rule in your mind. This means that even if you forgot to do it on day 5, you can do it on day 6 and you didn't break the rule. If you forgot to do it on day 6 as well, then you broke the rule/pattern.
> 
> Maybe pattern 2 in the original post was a little too extreme and that's why it seemed _rare_. If someone practiced yoga on day 1, 3, 5, 8, 9, 11, 13, 15, 16..., it wouldn't look very irregular. Describing this as "once every other day" or "once every second day" would be a lie. Is describing it as "once every two days" also a lie? ("Yes", according to the previous posts.)


That’s when we add a word or two like about or on average to cover some irregularities.


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## meijin

Yes, and that's another very interesting difference between the English phrase and the Japanese phrase. I really feel like asking all the English learners here in Japan "Did you know this? Can you believe it? In English, there's no idiomatic way to say 'once in two days'!" The teachers I've checked online all misunderstand that the English phrase "once every two days" means the same as the Japanese phrase "once in two days".


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## Copyright

_I hope by now that an understanding has been reached about how we say this in English, because I am closing this thread. Thank you to everyone who has participated. Copyright, moderator._


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