With stock ride height springs and less than -2 degrees camber front and rear on my RX8 and in spec toe in and out I find that I never have to flip the tires on the wheel. Simply moving the tires front to back after about 6 months keeps them evenly worn. My latest Rivals don't have a symetrical tread pattern anyhow so they probably wouldn't grip as well if flipped? I get one season of pretty regular autocross and street driving on a set of 140-200 wear tires here in FL.
By the time I hit the wear bars they are normally heat cycled out and I get a new set of whatever's best/cheapest.
My 86 Mustang is even easier with fixed diff and wheel spin no problem keeping tires nice and even. Those I can rotate twice if needed per year so no way I'll ever have to flip them on the wheels.