Here's an intersting idea:
For eons, all manner of animals have lived their lives according to the cycles of the Earth’s rotation on its axis, the moon’s orbit around the Earth, and the Earth’s orbit around the sun. But why do we observe the week? The pattern of living on a seven-day cycle—with one or two of those days set aside for rest—is a relative novelty. Only in the past few centuries, with Western colonization of most of the world, have the majority of human societies adopted it.
The case for the week was never airtight. It’s now weak and getting weaker. Most Westerners no longer observe a weekly Sabbath, and the coordination advantages of keeping everyone on the same uniform schedule have evaporated. So why does this arbitrary time cycle still dictate the rhythm of our lives? Is it time to abolish the week and find a better way to structure time?
But what would we replace the week with? We do need, I think, to have a specific unit that is less than a month to help mark our passage through time. The story notes that some societiets have observed three-day groupings and some have gone for 10. There are, as the article notes, fewer and fewer reasons to observe the standard seven-day week. But it's such a habit now that I doubt it will ever be replaced.
Hey, how about a fortnight? Let's do 14 days at a time. It's such a fun word to say, after all. Fortnight, fortnight, fortnight.