The most successful entrepreneurs I know work a lot, not because they think more hours=more output. It's just that they are so passionate about their product that they live and breathe it. If you aren't a founder, you simply don't understand.
And I was a founder and worked for seven years for the still-successful company. we made it a point to set good examples of working only while productive, allowing remote work, and not making any hourly demands on employees. knowing when to NOT work is more important than working hard constantly, especially when you are in a leadership position and don't want to set implied expectations on employees.
When I became a founder I clearly worked quite a bit more, but also found myself watching less TV and doing more reading, exercise...productive things.