Oddly, I'm sort of backwards...
On location, I'll restart. I always figure that my time to play on location is limited, and I would rather spend an extra $0.50 or even $1.00 to play a decent game on location and get further in what I'm doing instead of sit there and spend time trying to salvage a horrible game. I always feel like I'm on a clock at locations.
At home, I never restart. I figure I am playing the way I would have to in a tournament, and I'll set myself little goals after ball 1 and 2 to try to maximize my points. To me, it's a great way to play