Way way back as a wee PLS in grad school, I can distinctly remember thinking that I would never be PI material because I couldn't imagine working as hard as my advisor. Nights, weekends, holidays, didn't matter. If I sent an email I would get a response within an hour, and this was before phone-enabled internet access. The dude just worked. He has a family and they would often steal away to go skiing or boating, but if he was in town he was typing something.
I went on to do a postdoc anyway and had a second advisor with similar habits. "Great", I thought, "How am I going to pull this off?" My postdocs hours were decent, but there was rarely a time that I HAD to bring work home or work full tilt on the weekends. I did sometimes, but I was pretty successful without clocking massive hours. It was good.
I have been in my current position for 2.5 years (*shudder*) and something subtle has happened. I have progressively starting working more and more hours as layers of responsibilities have been dropped from above. I realized this weekend that my work-free days are rare, when the discussion of what we were doing over the weekend mainly centered around whether I was going to be working from my office or home. I don't know when it got to this, there wasn't a single event or moment when I decided that I needed more hours working, but after dinner and once we have read the Wee One her bedtime story, I'm off to my self-imposed basement banishment.
I don't know how else to get everything done that needs doing or keep on top of the bazillion little things that come up on a constant basis. Perhaps I'm just more inefficient with my time than others, but despite not seeing how I could work the kind of hours my previous advisors do, I'm starting to realize that it isn't really a choice. The choice is between getting things done and letting balls drop all around you. At the moment I am choosing the former, for how long I don't know.