Calum did a very good set of instructions for changing the rear hub a few years ago and this includes information on the rear brake as well.

https://www.mtwc.co.uk/wp-content/uploads/2018/01/M3W-Rear-Hub-and-Sprocket.compressed.pdf

The rear brake shoes are not the same thickness from new. It's easy to think that there is a lot of wear from a binding brake but this is not the case.