Most are unable to keep 100% focus on nothing but their families for even 1/2 of each day. Startup founders focus on their families less than many in other professions, but 3 dedicated hours per day is probably relatively close to average (if anyone has empirical evidence, please share).

As a father of two, you probably know that even when you're not directly thinking of your family, many decisions you make will be at least partially based on their well-being. So families usually aren't completely neglected in the time that they are not the main focus.

My father worked full-time with a one hour commute each way. I'd see him in the mornings, evenings, weekends, and holidays. While I spent less time with him than some of my friends did with their parents, I couldn't have loved, respected, and appreciated him more. In the time he spent with us, his actions showed how much he cared for us. I would argue that more family time with less consideration is worse than better care and demonstration of unconditional love within a smaller period.