Perhaps you've never been at a startup with recent college grads. 10 to midnight is a common schedule. That kind of work ethic isn't healthy, but recent college grads don't notice and even seem to enjoy it. What is does yield? A hell of a lot of code and an obvious boost in absolute productivity.

I would like engineers to work those hours with enthusiasm. My concern is that this wouldn't happen with a founder that is absent in the middle of their work day. The solution is to have a cofounder that works those hours, I suppose :)