I think Brian is probably the exception to the rule.
he seems to actually work with some data...
But how many times have we heard about lock time being better on x gun, or how much power a gun is running because of the way it hits a target or the time it takes to get there. How much wind a stripper takes or how much recoil it reduces. Shooters that don't cant or ******. Scopes that rangefind better than others. Etc... How is all this actually measured?
It's probably a good example that you are saying shooters are objective that reinforces my point... How have you measured this exactly?
From my experience of coaching many think they are but it's only when you get something to actually record the data do you see the difference between their perception and reality.