It is really hard to fold good
hands. Unimproved AA or KK is difficult to fold. Folding 2 pair or better is difficult to fold. We can look at our history and see how we did with these good, but not monster hands. So, in some ways, this is easy to analyze for ourselves, if we can look at how we did on dangerous boards and dangerous bets - did we ignore the signs or did we fall in the trap.
Betting on the other hand is tough to analyze, because we can never know if we were getting calls or folds. Generally, it is going to be higher EV if we bet, but this is sort of unknowable in specific situations against specific players. Again we can look at our history and see if we are getting more folds than we want, or getting more calls than we want.
In the end, folding and betting frequencies are important to keep balanced - we don't want to be predictable do we?
Good luck and God bless.