The lock assmy I think you are referring to is made of a pot metal and if not kept clean and lubricated, adjusted properly, the coach leveled (not having the door in a bind) and not rough handled, will last a pretty good while. Otherwise, I have replaced some only a couple years old.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7