(I am basing this on a "could-be" substitute, "3-day leave") But then, it seems that "a month's leave" sounds better, though it implies not really a full-month leave but just the month's (belonging to that particular month).
Which is right?
Top answer
The boss granted Jane a month's leave. The boss granted her a one-month leave. three days' leave ...
— Mister Micawber
The boss granted Jane a month's leave.
The boss granted her a one-month leave.
three days' leave ...
a three-day leave
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