If you're really enjoying working 80 hours a week, and everyone else on the team is too, I don't see a huge problem with it - provided, and this is a big "provided", that if anyone doing that wants to stop working 80 hours, or indeed take a bloody long holiday to recover, they can do so.

I know several extremely successful, productive people in different fields who work on the "work as long as you like when you feel like it, rest when you don't" principle.