I was in this camp for many many years, especially when I was single I didn't have notion of work and life. When I was in mood I work like crazy, then I might slack a bit or maybe went swimming at 1pm because there were no people. It started to change when I start living with my, now, wife and then it all get serious when we had kids.

They might be tiny, but they do require some structure and habits. I dont know how they do that, but there is going to be some serious door banging at 16:02 by our 16 months old signaling my allotted office time is over.