Aren't they symetrical front to back? If so, could you just flip them over? I guess the wear patterns would be a bit different...
Yes, but the object is keep the brakes operating with known parameters with regard to fade or grab.
The secondary object is to keep from having to remove and replace the brakes for longer intervals. If you go through the hassle of getting to the shoes, you might as well replace them with new shoes.
Many set ups require removing wheel, loosening hub from axle, removing six mounting nuts/bolts, removing brake backing plate from live axle mounts, "then" changing brake pads, messing with two front and two back springs. And once that's done, repeat the process, including the required alignment on the axle.