I have done many brake jobs, new shoes, sometimes new cylinders. I've never turned a single drum or had shoes arced. The drums wear "round" and never had one too thin. Shoe lining conforms in a few miles. Even if drums are grooved, lining conforms and stops vehicle. This is over a span of 60 years. Not saying you should not, just pointing out it's not a serious issue. It was done in the past to make easy money.
