The arguments about mature programmers being more efficient with less time are a red herring. The point is, given this guy working 40 hours a week and an equal

The arguments about mature programmers being more efficient with less time are a red herring. The point is, given this guy working 40 hours a week and an equally mature (presumably childless) programmer working say 70 hours a week, I'd go with the second one. It's just that there aren't a lot of the second to go around.