I ride in the fifth-largest city in the country, under conditions where I can often keep up with traffic and am rarely that far behind. I consider myself "traffic," therefore, and obey all the same rules they (ostensibly) observe. Except that I usually use the car right in front of me as a pick when proceeding thru stop signs/lights. We move together. And also "except" that I continue moving when they're stopped for the light, choosing which side of traffic to move on based on my evaluations of oncoming stuff and my chances of getting doored if I stay right. Those are related; I feel safest when I'm in the first pair moving.
Outside the city? I'm still pretty scrupulous about the rules except in "tree falling in the forest" situations. Kinetic energy is a *****, and I'm not into measuring it with my body.