I consider 'worn out' when the frame is worn/broken beyond normal repair. Anything else is just parts replacement.
Having said that, I broke 4 !
1. I was the Firearms Instructor for a LE agency. We had a member who was unsafe on the range, and refused to come out for addition training - even on duty time! I had to write paper on him, and the boss called him in and said "you have 30 days to improve, or you will be fired". He did improve, and within a year had completly worn out (i.e. wore out the frame beyond factory repair) of his issued S&W M19. Ammo was +P+ 110g .38 Spl.
2. I have cracked the frame of my issued S&W 6906, shooting 147g JHP 9mm. (Note, I was teaching at the academy, and had the keys to the ammo bunker - draw your own conclusions). It was the only 6906 we ever broke out of about 3,000.
3. I cracked the frame of a Colt .45 Auto, after 30 years of hard use with full power loads - around 5-8,000 rounds every year. (I had it welded, and it is still going strong.)
4. I also cracked the frame on another Colt .45 Auto, where the dust cover joins the frame. I had it welded and shot it for a few more years.
As you can tell, I shoot a little bit more than most people - about 10,000 rounds/year of all calibers, some years more. When I was on our National PIstol team, each year just before the Nationals, we each shot 10,000 rounds in one week.