This was especially important in the old drum brake days. You MUST have the shoes matched for curvature/ radius to the drum, or the thing will only contact a small part of the shoe lining, that part will be overworked and over heated and will become glazed. At that point you have terrible breaks.
All I was ever told, and all I ever did, for disk, was to "drive easy" for a few miles, maybe 10 or so, avoid sudden stops
I have literally turned thousands of drums and rotors in a previous life, at two different parts stores, one of which was established by my Dad. Back in those days, our small town had a number of small shops--and service stations--who did tuneups and brake work. There were some days at the store, where I spent nearly the entire day babysitting the lathes. Dad had an old Van Norman brake drum lathe, and a newer "Quick Way" rotor lathe, so you could do both at the same time.
The second store I worked bought a brand new Ammco drum/ disk lathe, with all three optional spindles. One was tapered, for the likes of VW and other small drums, one was larger and used on most stuff, and the other was substantially larger, for heavy truck drums.
I also have riveted my share of lining, including old '30s cars using bulk lining, because we could not get fitted lining, winch drum brakes, and heavy truck trailer shoes. I hated those, they are HEAVY
Dad's old riveting machine was all manual, all the time. The one at the second store was air powered, a bit easier.
And I almost forgot my point. I have arced my share of shoes. Dirty, dusty, and very likely life threatening.
