That's not non-sensical at all. It's completely plausible. In any task, fatigue results in diminishing marginal productivity, to the point where taking time to

That's not non-sensical at all. It's completely plausible. In any task, fatigue results in diminishing marginal productivity, to the point where taking time to rest and recover will sometimes boost total productivity more than spending that time working. Evidence, not blanket dismissal, is required to determine if that's true for Fridays.