Doesn't that mean a 10-day week (3 weeks per month) is a better fit? Only 0.5 days out instead of 1.5. Edit: though with the sinusiodal variation in the moon,

Doesn't that mean a 10-day week (3 weeks per month) is a better fit? Only 0.5 days out instead of 1.5. Edit: though with the sinusiodal variation in the moon, I guess it makes sense to divide it into 4. 3 weeks doesn't make sense for that.