There’s no correlation between hours worked and work done. I think this is why traditional corporate structures are starting to crack at the seams, and the distributed model companies like Automattic, MySQL, SocialText, and many others use will start to gain real legs and acceptance. The best example of this was at a place I used to work: after lunch everything seemed to shut down. Several people obviously got very sleepy after lunch and would spend 2-4 hours of the afternoon on auto-pilot. (This was me sometimes too.) It would have been infinitely better for them to take a one hour nap and get back to productive work than spend 3 hours in an obviously hampered state. Happy, healthy, well-rested people work orders of magnitude better.