I suspect warped rotors MIGHT be due to sitting with the brake pedal depressed after a hard (especially downhill) stop. Like when the light at the bottom of a hill turns red and you were going 50+ MPH and sit at the light while it goes through the entire cycle.
I try to avoid that by stopping a few feet short and rolling forward intermittently while waiting for the green signal.
By the way, isn't it amazing how many traffic signals are located at the bottom of hills? OK, OK, I know that, in the good, old days, like before the internal combustion engine made road building easier, it was natural for roads to follow valleys. Just the same, traffic signals at the bottom of hills aren't a great thing for brakes, gas mileage, accident rates, you name it!