I keep a little notebook next to my TT. Every time I play an LP front to back I make a hash mark. I count each hash mark as 45 minutes (not trying to be perfectly exact, it's just the number I chose to use). After I make 10 hash marks, I write the date next to my hash marks and then add 7.5 hours to a running total in the far column. Then I drop down a line on the note pad and start my next set of 10 hash marks. Using this method I am able to use the dates to see how many hours over a space of time that I listen to my TT (it's never as much as I'd like). It also lets me know the age in hours on my stylus, albeit my method gives me an over estimation because most LPs come in under 45 minutes. I just use 45 minutes because it makes the quick math easier and back in the day a 90 minute cassette tape is what I always used to record 2 LPs, with one record per side. Surely this must be a common practice in order to know the amount of usage/wear on one's stylus?