The really professional brake shops used to grind the brake linings to a slightly smaller radius than the drums, so the first point of contact was in the center of the brake shoe. As the drum flexes slightly, the full surface of the shoe would come into contact with the drum. A set of standard-diameter linings and a slightly oversize drum fits about right without any grinding. If the shoe can rock a little with the main point of contact in the center, you're good to go. VERY few shops still grind linings to fit drums, over dust concerns. Back in the days of asbestos linings, the grinding dust could be deadly.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!