I had to replace the extractor on my hi power after 20 years and thousands of rounds. I sent my Sig P220 in to have all the springs replaced along with a cracked slide at about the 15 year point..I think it was 15 years. No idea how many rounds are through either weapon as I don't count all of them, but it was "thousands". I replaced the gas rings on each of my AR's when one of them started acting a little sluggish. I believe the gas rings had been installed for 9 or 10 years. I replaced magazine springs on a couple of mags when I felt they needed it, no idea on the interval. I am sure I missed some stuff, but that is all I can think of at the moment.
I don't think any of these failures were due to neglect or a lack of cleaning, but maybe I was doing something wrong that caused the AR gas rings to wear out, or the slide to crack on the Sig and the springs to wear out.