I always recommend replacement on the basis that the drums aren't coming off again for perhaps another 3yrs. The facings will be soaked by then. Every 36,000 used to be Peugeot's interval. I've noticed Ford service schedules now specify drum removal only in the event of leakage.
I grew up in an era when wheel cylinders started to leak as the car drove out of the showroom. Who remembers Fiat 126 cylinders, which used simple 'O' rings?