With or without a family, the reality is that you work in spikes.
You have times where you work much less than that on client projects, maybe just 50% of that, and use some of the "free" time to tinker, learn, improve your internal tooling etc. And of course spend more time with family and friends.
Then there are times where you have to squeeze in as much (billable) work into a week as possible. Deadlines need to be met, quality & testing needs to be rock solid.
Then there are times where you spike up with work and start neglecting family and friends. It's just how it goes. No amount of planning can prevent these spikes completely.
I'm sure there are exceptions, but generally you are in part hired for your flexibility and high engagement. You give certain guarantees that employees don't and you make absolutely sure that those expectations are met.
But again, it's an ebb and flow thing. Or it should be. There needs to be times where you decompress for a while, look at the big picture and sharpen your tools.
I live in Europe as a subcontractor and I work 32 hours per week. That's billable hours, which excludes travel/commute, bookkeeping, trainings, and searching for new projects. It works fine with family. I do my own bookkeeping and taxes.
