Bsa buffer washer cheese period?

[Dornfelderliebe]

How long does it take for a BSA Airsporter or BSA Mercury buffer washer take to turn to cheese and jam the piston in the cylinder? Five year? Ten? Twenty?

Just replacing one so need to know the service interval... or best just to put at new one in at spring renewal?

My Meteor and Airsporter went 20 years without jamming up. However I don't know how long they'd been cheese.