To be honest myself and my co-founder work closer to 35-45 hours a week. We also do about 20 hours of technical work a week, and the rest covers the business overhead (accounting, client relations, business development, project management, etc).

Our goal in the long term is to bring us down to 20 hours a week overall, also, but that's probably several years away. Still, we both feel that as co-founders at a small business keeping it well under 50 hours feels like a win.