A decade or so ago, I kept track of each LP side played after getting a new cartridge. Nothing fancy, just a sheet of paper with dates and hash marks for each side. I estimated 20 minutes per side so one hour for 3 hash marks. After doing this for an a few months following each new cartridge, I discovered that my LP listening time is very consistent, averaging 30 hours per month. Now that I know this, I no longer bother keeping track. I just know that every year equals 350 hours more or less. I also know from experience that my Benz MC cartridges last slightly more than 1000 hours before they need replacement or need a new stylus, which was the point of the article Bill posted. I know this because they start to become less clean in the highs especially in inner grooves. For the last 12 years or so, I have mostly used the same cartridge—a Benz LP which I happen to like very much. It has been retipped by Soundsmith twice and I plan on sending it back every 3 years for as long as it holds up, hopefully forever. The Benz is like a brand new cartridge after each retip.