I would be interested to know why someone would keep stats. I keep mental notes about lane to lane characteristics, but I'm curious on the reason behind keeping results from every frame.
Mental notes are good, but certain lanes have certain special traits to them as well. I can go back and see what I was using, where I was standing, and what my target was for each lane in a particular house. Bowling in a couple different houses over various lane numbers I cannot keep up with exact stats.
Before apps I had steno pads that I kept notes on, a different steno pad per house I bowled in.
Also knowing what percentage of a certain pin you are leaving or a missed spare conversion you need to work on may help in some people's scores.
To each their own, if it helps: use it, if it don't: stop.