I wouldn't say that I log LOTS of factors, but I do note the date, range, gun, ammo used, # of rounds, shooters, and make notes if something happened that I want to track like FTFs or what my score was if it was a match.
If/when I sell a gun I would like to be able to honestly tell the buyer how often it was shot and how many rounds are through it. Much like selling a car with records.