I work at an 8-hour a day facility. I work more efficiently, and focused than my days in 10-14 hour places. Also, I come into work, feeling fresh, looking forward to work.
When I work at the long-hour places, the pace is so slow that it is boring. I think that our systems slow down to prevent burn-out.
It's funny how employers think that long hours means they're getting more out of their workers. That is not the case.