Well...if one's going to be balanced, they should be certain to get the recommended amount of sleep for their health's sake. 8 hours is the often cited mean, no?
So, work 12 hours per day + 8 hours of sleep... we're at 20 hours per day accounted for, thus far.
Let's not forget a bit of exercise everyday, health comes first. Say 30 minutes. We will be conservative and say that our hypothetical profesional only commutes 30 minutes per day total as well (i.e. big cities, forgettaboutit!)...better not have to stop at the grocery store for some milk either!
We're at 21 hours accounted for...add in 30 minutes total for daily bathroom tasks (showering, brushing teeth, flossing, sitting on the throne, et al).
We have 2.5 hours left with our conservative figures.
Does 2.5 hours leave one balanced in the family life category? It depends on the person...What does only 2.5 hours permit...eating dinner (unless you missed it), cleaning up and watching a TV show?
But, don't forget we excluded any house work, maintenance, etc that will need done on occasion. I don't know many wives willing to get in crawl spaces to fix leaky pipes.
We also skipped the idea of that little thing called "call". And we skipped having any personal hobbies that you enjoy. And we skipped taking the time to have sex with said wife...unless that is only a weekend thing for some professionals.
If one doesn't have kids, I would agree with you. No problem. But kids need parental guidance/support every single day of the week -- not just on weekends.