# Expression regarding a periodic task

So, if I have to do a certain task during a whole week but with a 3-week gap. For instance, in a 3-week period I will have to do that task for 1 week, in a 6-week period for 2 weeks, not in a row, of course, and so on.

1. One work week for each 3-weeks.
2. Once in every 3-weeks.
3. ...

Which is the best way to express this work schedule rotation?

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Others have answered, but side note: Don't hyphenate an adjective with a noun in general. Just write "for each 3 weeks". You only hyphenate when the adjective and noun are being used as a compound adjective to modify some other noun. Like, "for each 3-week period". Here "3-week" is acting as an adjective. And it's conventional to spell out numbers less than twenty or so, so better still is "for each three weeks" or "for each three-week period". – Jay Oct 4 '12 at 13:44

Why not simply say one week out of three, as in

We work one week out of three.

or

You will work one week out of three.

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That's it, yhank yoou a lot :D – utxeee Oct 4 '12 at 12:46

Assuming the schedule is linear/predictable, I'd refer to it as, "I work every third week"

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Every third week you could be working for a day, not necessarily a week. – Kris Oct 4 '12 at 13:40
• One work week in every three-week period.
• One work week per three weeks.

Don’t hyphenate as a noun phase, only when making a compound adjective. And don’t use numerals; use words.

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