My 32' 5th wheel trailer/rubber roof is a '98 model. I do a quick roof sealant/roof fixtures R&R as needed in the spring and in the fall just before I winterize for its 5-6 months winter sleep.
The roof sealant did great till '08 when sealant around the bath room skylight started coming loose in one 10" long piece (no leaks). I pulled all that was loose and used self leveling Dicor in those spots.
Years later the front cap/roof sealant showed small cracking. Removed what was loose and more Dicor self leveling sealant in those spots. Thats all I've ever done to the roof sealant since the unit was new.