Drum systems are deceivingly complicated. Drums can wear bell shaped, "humped" in the middle, with all kinds of variations. Plus they wear with a ridge on the inner and outer edges which interfere with new shoes. In other words, new shoes won't fit well into the oddly worn drum
So you turn it what then?
If you turn a drum "much" the drum of course becomes larger and so the shoe now rocks in there with only the center area of the lining touching, and this does two bad things: First less shoe lining is touching the drum, so there is effectively less braking force/ shoe area. Second, because the middle/ center area of the shoe is doing the work, that part gets hotter and GLAZES, which then makes it LESS effective, and now you have very very poor brakes. You can push on the nice hard pedal until you break something and IT JUST WON'T STOP
So you have to have the shoes matched to the drum which is called "arcing" the shoes on a special machine---which I bet not 1 shop in a hundred has anymore. ****, nobody has drum/ disc lathes anymore, either.