On my bike I have an FSA headset Orbit X-CX which has cartridge bearrings. I re-grease the headset a few times each year and have recently replaced the lower bearing after ca 13,000 miles. The upper bearing still feels smooth.
On a loose ball style headset if badly adjusted or after excessive use the cups would wear. With a cartridge bearing the bearings run on the cartridge itself which is replaced. Does this therefore mean that the cups should last the life of the bike?