Does working Overtime ever work?

Ask 10 developers what they think about startups. You'll get a mix of responses involving risk, finanancial deprivation, and stress. But the one thing everybody will mention without fail is overtime. Startups are known for their frightening tendency to encourage developers to sacrifice everything at the alter of the 18 hour work day. The question, therefore, is how effective is overtime and should it occupy a place in the startup manager's toolbox