Regular periodic maintenance of removing the drums, cleaning the dust, and adjusting the shoes will give longer life to the brake shoes and the front brake pads. Very dusty and misadjusted rear brakes can cause premature wear of the rear shoes, poor stopping ability, and a heavier load on the front brakes, causing front pads to wear out quicker as well.
Use a small screw driver to adjust the adjusting start wheel. It will only turn one way, because of a stop mechanism. If it does not turn one way, turn it the other way to adjust the rear shoes outward, which brings them closer to the inside of the drum surface for better stopping power.
Click picture for a Closer view of adjusting.
Click picture for overall description of rear drum brakes.