There are so many factors that go into this for medical students, residents and attendings. But, the biggest determinant is the individual. Yes, specialty matters, type of practice matters, but at the end of the day, it is the individual that makes the call on how much time they are willing to spend doing different things.
By hours, I am in the most demanding specialty there is. My residency was by all accounts among the busiest. I averaged about 100 hours/week for all 7 years. While that may have been the norm years ago, most places are clamping down pretty hard at least nominally. We got much better as I became more senior in my program at taking care of each other and looking out for each other, but the first several years, there was none of that. It was pretty brutal, every week.
I had one real hobby in early residency, rock climbing. I competed in endurance competitions and trained 10-15 hours/week. I would sleep in the back of someone's car on the way to the gym, climb 40-50 routes, sleep in the car on the way back to my place, finish my note and then pass out. Then on my weekends off, I'd leave Friday night, drive through the night (8-9 hour drive), climb all day Saturday, sleep, climb all day Sunday, start the drive back and then sleep the last 4-5 hours of the car ride and arrive back in time to start work at 430am on Monday. Now, at that time I didn't sleep much more than 4-5 hours at baseline (now 5-6). But, was it doable? Yes. I took my hobby seriously and performed at a relatively high level. But, it meant sacrificing everything that wasn't my relationship with my wife to do it. I gave up a lot of other hobbies, I gave up a lot of down time/alone time and focused on that.
If I can do that in the specialty that I am and the residency that I was at, I firmly believe that you can do whatever you want. You just can't do everything. 168 hours/week that is what you get. For me it was all about pairing everything down and living my life in 15 minute increments. I forced myself to justify spending time on everything in my life and was forced to cut out many things. At times, that included SDN. Contributing here is something that I enjoy doing, so I typically find my way back eventually, but it like everything else is fungible.