This would be great - keeps review roll-up granularity similar:

- 7 days roll into a week

- 4 or 5 weeks roll into a month*

- 3 months roll into a quarter

- 4 quarters roll into a year

Without quarters there is a leap in the granularity between months and years:

- 7 days roll into a week

- 4 or 5 weeks roll into a month*

- 12 months roll into a year

*Mapping of weeks into months is a separate question - I keep weeks whole and assume the week is in a particular month based on which months the majority of its days fall.

E.g. Week 31 this year falls into July because 4 of the 7 days are in July.

I would totally use that.