9mm Sig P229 and P229R's, using the latest mags that Sig made for them (this was circa 2004-2008, I wouldn't want to bet on sig reliability today), all ran flawlessly for over 20,000 rounds a year, year after year, in mud, rain, dust, desert, cold and hot. Clean or dirty, as long as they had enough lube, they ran. I only had about 100 samples to look at, so not a huge number, but better than most. Some of those guns were replaced from time to time, but not because of any catastrophic failures.
Note that I'm referring to reliability here, not overall durability. Occasionally a safety lever would break, or some other small part. As soon as it was replaced (armorer level maintenance), the gun was back up and running.
I've never seen a group of guns that didn't need something, but my experience is limited. I do expect though, that I never will see 100 guns run for 100,000 rounds with no parts breakage or reliability issues.