Talent is going to be a much bigger variable than hours. When you work 80, 90, 100 hours a week you're hitting diminishing returns in a big way. Also, even at 40 hours a week, very few people achieve maximum efficiency every second from 9 to 5.

I think rather than worrying about hours, entrepreneurs and other people who want to be highly effective should worry about how to improve their skills and focus when they are at work. There's a way in which a 100-hour work week can become a scapegoat... if you fail to produce at least no one can say you weren't committed. However, if you are truly only interested in results, you need to step back and ask yourself objectively are you making the best choices or are you just trying to cover your ass? I realize that outside perceptions actually do matter a tremendous amount to business success, but the bottom line is that the best person to build something is not simply the person who is willing to work the longest hours.