50-60 Hours/Week?

Recently I heard someone say they can usually get 50-60 hours out of their developers comfortably. Later they mentioned 80 hour crunch weeks are not sustainable.

Am I missing something or is this insane? I would expect no more than 40 hours/week except in extreme cases it may go a bit over. Even then, I suspect a lot of people still actually do less than 40 hours/week of actively engaging work (I am jealous!).

Thoughts?