Sure you aren’t confusing Hartmann with Jans-Joachim Marseille? He was the one noted for uncanny accuracy, very few rounds per kill, and deflection shooting, not Hartmann.
Personally, with all of his 158 kills vs. the British, I think he was the greatest fighter pilot of all time. Marseille’s kills vs. Hartmann’s is like comparing Div. I and Div. II football records.
I might be confusing the two. Its been a while since I was reading up on either.