I have four Shure phono cartridges in their original boxes and never used. What is the life span of a cartridge? The models are M24H; M11HE; M99E.
The cartridge body does not wear out.
The stylus tip lasts between 800 and 1,000 hours of playing time.
The stylus bushing is an elastic material, and can harden over the years, even when not used. The audible symptom is lack of bass, and/or mistracking.