I had a big fight with the other co-founders of a company regarding work hours a while back. Most programmers hit something like up to four "good" hours per workday, the biggest problem is capturing those hours while they're at work. A separate problem is hitting those hours while they have access to their manager or colleagues that can help them overcome small but time consuming problems.

I'd like to think that programmers have a creative or even artistic occupation (personally I'm more manager than programmer these days). Forcing something creative out is rarely good or even possible. The majority of the employees in my organization are in sales. There's a limit to where you can push that for most people too, but it is a different kind of limit.

Personally I've only put in proper 80-hour work weeks something like three times working as a disillusioned startup "employee" or as a consultant in extreme crunch because of launch marketing costs. Sure, something is deployed and it you certainly feel a sense of accomplishment but it's not something that should be used by any serious company expecting people to stay longer than a year or two.

With that said: people checking/answering their email or checking error logs at odd hours "for free" really do bring value to a company though.