I don't see how. You are making assumptions and claims for others with no support. To me that week.day number looks more complicated and less meaningful than plain days.
Perhaps weeks seems to make sense since we sometimes use them for offsets and ranges, like "this project will take 6 weeks" and figuring out how many days that is is inconvenient. But if we were using days then we simply wouldn't use groups of 30 or 7 for things like that, we would use groups and multiples of 10 or 5. We'd probably end up using kilodays and millidays too instead of years or minutes, and years would be arbitrary, but 51.9something weeks is already arbitrary anyways.
And as that # of weeks example just showed, .day is ambiguous with decimal fractions of a unit.
All in all I see no special obvious rightness here. It's kinda crap actually.
Perhaps weeks seems to make sense since we sometimes use them for offsets and ranges, like "this project will take 6 weeks" and figuring out how many days that is is inconvenient. But if we were using days then we simply wouldn't use groups of 30 or 7 for things like that, we would use groups and multiples of 10 or 5. We'd probably end up using kilodays and millidays too instead of years or minutes, and years would be arbitrary, but 51.9something weeks is already arbitrary anyways.
And as that # of weeks example just showed, .day is ambiguous with decimal fractions of a unit.
All in all I see no special obvious rightness here. It's kinda crap actually.