Expected milage from 5th wheel brakes

Say what you want but my brake shoes say differently. The shoe that engages going forward has much less material than the one that is engaged when backing up! And yes they are operating properly! And both my shoes are primaries because of how the brakes are setup. So mine can be switched. The amount the adjuster gives to the other shoe is minuscule!

And yes I've been doing drum brakes for near 35 years now!