I keep, and have kept, a record of each round fired in all of my handguns. I started this around 1958 or so when I was in the Army. I was the company armorer and we kept a log book on our 106mm recoiless rifles. Seemed like a good idea and I started one for my Ruger Blackhawk. I labeled my ammo boxes with loading data, and when I returned from the range logged this in by counting the empty cases. I then marked the number of rounds remaining on the box label.
I found it interesting that folks who kept a "ballpark" count, and didn't shoot as much as I did, actually had higher round counts in their guns. But, when a gun did malfunction, and they all will sooner or later, I knew how many rounds had been fired up to the break-down.
What started as a matter-of-interest thing became serious years ago when I wrote a gun column for the old Tennessee Sportsman magazine as oftern the question came up about how many rounds could one expect from a new gun or something like that.