It I’m paying someone by the hour, then I’m fine with them leaving when they are done with their work. However, if someone is salaried I expect them to put in a solid 35-40 hours/week. At this point I’m worried about the morale of the other devs on my team. The last thing I need is everyone getting pissed off because they think I’m coddling a Prima Donna.

One more note: the best developers on my team look for more work when they have finished their tasks. They are focused on the success of the overall team.