My two full size CZs with safeties (75B, 75 Shadow), I've had these parts break/fail. ( Both have 60k RDS or maybe more rounds through them.):
ranked most likely to fail first:
Slide stops
Slide stops
Older style OEM trigger springs.(2) The newer trigger springs haven't failed since
Extractor (only one, where the blade chipped slightly)
Competition Hammer & Sear ( one of each when the sharp edges wore rounded between the sear and comp.hammer)
Pins that "I" have damaged when removing/installing them: Front Sight pin (2), Firing pin safety pin (1)
No pins have failed on their own.
No Firing Pins have ever failed. (I did install extended FPs with new springs a long time ago on both pistols)
No Firing Pin Springs have ever failed.
No hammer spring has ever failed ( I have lightened both springs for my pull weight preferences)
Stock mag springs will eventually "weaken" and need replacements.