Totally agree. I don't see how people can be productive working >60h/week and doing mental job. I find 30h/week to be perfect as I can't keep concentrated more than 3-5 hours straight, so that makes two streaks (2-3h) and a coffee break working day Monday till Friday. If I'm forced to work longer hours, I find my mind wandering around, rewritting the same code over and over or reading HN. Of course, there might be some short-term mission critical periods when I can honestly put ~10h/day, but it's an exception that must be justified, not a rule.
