Another thing to check that wont cost you anything, is check that your pads/shoes arent sticking in the guides/against the backing plate. When you are resurfacing or replacing your rotors and replacing your pads, make sure your shim is cleaned of all rust and a thin layer of antiseize is used on it. The pads should move relatively freely so that when your caliper squeezes, both pads act on the rotor. It might seem like something so obvious, but ive seen it happen all too often...one side wears faster than the other.
Same thing goes for the rear. Add a thin layer of antisieze on the backing plate where the shoe rubs(but not on the friction material!) If your shoes stick then you dont get the self acting servo action going fully and that means not full braking power either.
Another disadvantage of not having proper lube on these areas is if they do stick, they will drag, thus glazing everything....and not to mention breaking your wallet with poor fuel mileage, and prematurely worn parts