It is actually your tuner, the Ezell tuner, that I do use and I appreciate the time we spent on the phone. As a mid-range and long-range F-Class shooter it is sometimes easy to observe that there is more vertical in the downrange group than expected, and especially so, if you feel that the rifle has gone out of tune. It is more difficult to comprehend what has occurred in windy, heavy mirage, late afternoon sessions coupled with some fatigue.
Even using your method, it is not at all easy for me to see the pattern after 5 or so down range shots, recognize the pattern and have a good idea of how to turn the tuner. I honestly can't seem to remember more than the last two shots.
I use tuner because I believe it is better to have one than not, but I also know that I can tune a rifle w/o one just as well for a specific condition. If that condition changes dramatically like Spring to Summer here in Georgia, then I have to develop another load rather than finding a better tuner setting.
There is also the idea that a competitor might be able to improve performance during a match with a tuner change. To be honest, I have not even tried that because I am not confident that I see a pattern that I recognize and know what to do about that in the conditions mentioned above.
One last bonus thought. IMO, it would diminish this sport if all you had to do was plug in your case brand, cartridge, powder, projectile, primer and barrel details into your phone and out popped the perfect load. Finding a tolerant load or taking a risk on a hot-rod, narrow windowed load is all part of the sport.
I have a great deal of appreciation for all of you guys that have created tools, methods, apps and accessories that make our sport better. It's got to feel pretty good knowing you've left your mark in a very positive way on a sport you enjoy.
Hank