I do my own service when the reg just does not feel quite right. Usually it only needs a minor second stage adjustment but a total overhaul on both stages maybe every 2 or 3 years. This is done mainly to replace the rubber parts as they have the shortest life. I have no issues with corrosion or muck build up as I clean them very well after each dive and I do a fair amount of mud dives when I am salvaging something. I got rid of my newer regs and replaced them with old Scubapro regs from the 70s so there are no plastic parts that need to be replaced.