Adding another Amen here. I work from home, and I can get done in an hour or two what most of my colleagues take all day or even 2 days to complete. Why? Because I'm left alone!
The only time I work is when I want to work. That means, in order for me to tackle a project, I have to be motivated. When I'm motivated, I get the task done better, more quickly and more succinctly the first time.
If I'm forced to sit and stare at a screen and made to feel guilty when I'm not working, I'll never be motivated for anything. And working on something when my brain keeps saying "Fuck This!" is damn near impossible. I'm more likely to put some sort of half-assed hack through in such a scenario.
Some people, like you and me, Aaron, can motivate themselves and make sure things get done on time without someone standing over them. The manager standing over you scenario comes from a world where work is supposed to be dull, soul-crushing and horrible. Yer not supposed to want to go to work, so we have to stand here and make sure you do everything.
Helps to be passionate about what you're doing.
But yer also very right about dividing between work and life. I often find myself replying to work emails at midnight on a Saturday night, or working on a project on Sundays, or even while on vacation. In such cases, it helps to have a spouse who can shout at you to put it down.