Weeks are quarter months. Or are supposed to be. Months have been screwed up for a long time now.

I can imagine in prehistorical times keeping track of midrange time by the phase of the moon, if months were kept synced to the moon we would probably name weeks as such, waxing gibbous, waning crescent...

On the subject of keeping months in sync, I can imagine having a fun festival season around the weird 13th month(all months being 29.5 days long) that bisects the new year.

Aren't modern months made up as well? They are not in sync with lunar cycles anymore.

Well, seconds, minutes, and hours are also arbitrary.