Originally Posted by pawoSD

Since brakes are a fluid/hydrolic system, the pads/pistons in the caliper move to press against the rotors based on how much pad and rotor there is left, when you release the pedal and your pads are 90% worn and maybe half the rotor life is left, the pedal will travel no further as the pistons do not move back to their "with new pads/rotor" position. They simply move away enough to not apply any force to the rotor, which is extremely close to it. Thus when you press the pedal again the same amount of fluid force/pedal distance is used if the pads are 10% as when they are 100% as the pistons are moving the same exact amount of distance they did to begin with in order to compress on the rotors.