# Frequency/quantity in a/one month

1. There are four seasons IN a year
2. I do it five times IN a year
3. The girls meet me twice a month
4. He smoked five cigarettes IN a day
5. They finish five books a day

Which of those (is/are) clunky?

• The only one you really need the IN for is 1) "... seasons in a year". 2),3)4)and 5) are all more natural without IN, you can use the preposition if you like, but it's clunky. Every year must have four seasons, by definition (at least it is in most of the English speaking world). You must use IN when defining a whole in terms of its parts. So this is a different construction from the other examples. To help see the difference: it's fine to say "I work twelve months a year", but I must use the preposition when saying, "there are twelve months in a year" Commented Aug 7, 2019 at 15:48

When describing repeated actions, you can use in if you're referring to a specific time period.

He smoked five cigarettes in one day.

I did it five times in a single year.

This is often used to express that the particular time period was exceptional, although it could just be describing an exemplary period.

But if you're describing typical behavior or average frequency, you don't use in.

He smokes five cigarettes a day.

I do it five times every year.