Ray Houston over at LosTechies has a post about not wasting time. On the surface, what he says makes sense. But consider this:
“After a good day of pairing, you feel exhausted because you put in a real day's work. You were engaged the entire time. Why don't we hold ourselves to the same standards when we are programming solo?”
It is bad to have your workers, in any field, feel exhausted at the end of a day’s work. This pretty much guarantees burnout in your workstaff.
Except for those periods where there is a really important business imperative for working extra, you should never expect or allow your workers to feel exhausted. This is local optimization gone way wrong and bad advice all around.