I'm not aware of anyone wearing out the frame or slide, yet. There are quite a few people on this forum who shoot enough to have gone through multiple rounds of replacing the normal wear parts, primarily springs. I seem to be lucky, because I have replaced my fair share of springs in the last 13-14 years, but to date, I've never replaced an extractor or firing pin, for example.
The metallurgy on 75/85 series pistols has improved over time, and I believe it is continuing to improve, albeit at a slower rate. When the B series was introduced, it coincided with a significant upgrade in the metallurgy/service life.
The "official" durability requirement, as published by CZ-UB, was initially only 5,000 rounds fired (9mm) in 1975, but this specification was increased to 8,000 in 1980. However, the same source indicates that all pre-B pistols tested to date have exceeded this by a minimum of 30%, or at least 12,000 rounds fired. The source notes that the technical requirements/specifications were increased again in 1991 and 1995, but I cannot find the newer figures. See pp. 46-47, Pazdera & Skramoussky, CZ 75: The Birth of a Legend (CZ-UB, 2005). In context, I don't believe this was "hedging," so much as avoiding the need to list all of the different models and variants, as well as chamberings other than 9x19mm, available after 1986.
Presumably, these pistols were tested with military loads, not nominal SAAMI specification commercial 9mm loadings. These were the durability requirements/specifications formerly provided to military and police customers/purchasing agencies.
Personally, I have fired at least 8,000 9mm cartridges each in several different Type B 75/85 series pistols with only routine changes of the recoil springs, and the occasional firing pin spring. In my case, I have shot a fair amount of SAAMI +P and the equivalent in handloads. I know/know of people who have fired at least 12,000 9mm cartridges each in either Type A or Type models (or both). Some of these people have replaced extractors, etc., but none of the major parts (frame, slide, or barrel).
At least one person of my acquaintance opted to replace a barrel at @20,000 cartridges fired. I hope he will post here soon, as I believe this was more due to a perceived need than an absolute requirement. This person shoots a fair amount of SAAMI +P 9mm or the equivalent handloads, IIRC.
I would expect someone who is keeping careful notes to observe some minor increase in the dispersion (group size) at @12,000-15,000 cartridges fired. I would suspect that someone who is not properly documenting this would not notice for quite some time. The barrels of 75/85 series pistols are still hand-fitted to the slide; they are not "drop in" replacements. To be clear, this fitting is done by professional gunsmiths, but on a large scale consistent with mass production techniques. The goal is a very high average; each individual pistol is not "accurized" to the degree one would expect from a custom job. However, the nature of the design, construction, and specific techniques employed allow this type of accurization if the owner desires to do so later.
In other words, you would expect to see some degradation of the grouping long before the chamber or the bore wore to the point of requiring replacement in an absolute sense. This is just the normal life cycle for an all-steel pistol built with these techniques. At the end of the day, it's an excellent embodiment of the "no free lunch" principle. If you want a traditional all-steel pistol for @$500 that is also tight and accurate, this is about as good as it can get.
