I own a small start-up and struggle with work life balance. I'm a night owl and generally not terribly productive in the morning, but once I hit my stride in the afternoon/evening, my productivity continues to increase and I often find myself plugging away at 3-5am. I have found that it's in my best interest for throughput to continue when I'm "in the zone", but it does create some friction with the spouse.

I'm very interested in how to define the "enough work for the day" question. Or we could just listen to Dan Reeder: https://www.youtube.com/watch?v=xNWhiXxdbWk