Keeping Track of Vinyl Playback Time

I don’t. When I hear a problem with my stylist then I will know it is time for maintenance. 
 

My last cartridge boasted of +3,000 of play time. I had it for over fifteen years and never reached it. Sold the turntable. I was working then… I listen to more music now. 

I have made an excel file.

SOTA has an accessory for some of their turntables called the Roadrunner.   It uses a Hall effect sensor to feed back the platter speed to the motor controller for precise speed .   One nice feature is that it also has a counter in it that keeps track of stylus time 

@rdk777: Fremer reviewed a cheap little accessory that is a timer for stylus'. Look for it in the Stereophile Analog Planet archives.