In total, probably 8-10 hours a week.
I work full time and live alone. So I lose 40+ hours on the front end, plus most nights & weekends doing all the chores that go along with being a functional adult. Recently, I also added working out into my routine, and that pretty much broke me. Yes, there's enough time to survive, but ya reach a point where you wonder WTF - how come I never have any fun anymore? I've now reached the point where I've had to force free time into the schedule. I now purposely fuck off Wednesday nights & Saturday mornings. Everything else is full. =(
At my first internship, they made me go through an entire bookshelf of safety training manuals that felt like they were written by the local staff. They were all full of things like "don't put a pipe on the end of a wrench to give you the leverage you need to do your job" and "don't forget to clock out at lunch or we'll have to assume you were gone for exactly one hour". Took me a moment to realize they were in fact telling me exactly what to do, but in a way that would also cover their asses. Always thought that was clever.