Rotor Distortion and the Hub Flange
The steering wheel shakes when I apply the brakes. This is probably the most common complaint when it comes to the brake system. Sometimes this vibration is severe. This question speaks of lateral runout and thickness variation. These are real problems and result in rotor replacement and machining. But this vehicle requires frequent rotor replacement. Something else is wrong here. Something is causing this recurring pulsation.
It reminds us of the importance of inspecting components like the steering knuckle, hub and hub flange before replacing the rotors. Rust, debris, or a protrusion like a burr on its surface will result in an uneven mating surface between the flange and the rotor. This burr on it's surface will cause the rotor to wobble. If the problem rotor is on the front, the wobble will be felt in the steering wheel while braking.