Indeed it is becoming ever more common in trads. When I was last at Techniques, James was saying that rear wheel cylinders have almost become a service item for cars that are not being used for long periods.Expensive too at MMC prices.
The issue is made much worse if the handbrake is applied during these periods of rest , because the exposed part of the pistons corrodes and eventually won't slide inside the cylinder , stainless sleeves will obviously help here, and this is the route I would take rather than stainless pistons. Leave the car in gear , or with chocks if it is not being used.
I now back off the adjustors, remove the drums and have a good look at the cylinders at each service. I also find it is worthwhile to deglaze the shoes lightly. I inspect the pistons for any sign of corrosion and use brake grease on the exposed metal surfaces under the rubber caps.
In light cars like ours the rear brakes do not provide much of the stopping power, so the pistons don't move much at the best of times (competition cars excepted of course) so it pays to keep a watchful eye on them.
