At yesterday’s MotoYard track day one of my clients had an on board timer. He did a few sessions before deciding to hire me.
I made my first set of adjustments based on what he said about the bike and what I felt by bouncing on it in the pits.
When he came in from his next ride he showed me his timer, 3 seconds a lap faster and he said it took less effort. Sounds like a good way to spend $50 to me!