3 to 5 years is a long time for any cartridge. If you want to count hours, the usual time for replacement would come around 800 to 1000 hours of play. This varies greatly depending on the condition of the records you play, and if they have dirt on them. It could be good even out to 1600 hours, if well taken care of. Even if you don't play the cartridge alot, after 5 years, the rubber donut that is part of the suspension usually gets hard, and is not sounding the same as when new. This is why even a NIB cartridge that is over 5 years old is questionable as to its performance levels. Shelf life of the rubber.
