Frustration will always be a big part of the game, and experienced even by top-class touring pros. Mainly, all of us spend a great deal of time frustrating at our failures to repeat what we did last week, or better yet, just yesterday. No matter how good you are, you will never be able to repeat what you did twice, let alone do it week-in and out.
I always take "signing" as an example ----- no human being can repeat his/her own signature exactly the same way that was done before --- even though it requires only the smallest of movement. You can only imagine the time you need to build consistency in the golf swing, which asks for a lot of movements and good tempo/timing.
However, with lot of repetitions ----- they can be a positive improvement. All top players may have different swings and techniques to strike the ball, but one thing that they do the same ---- they practice a lot, in order to memorize those movements and be able to do them under tournament pressures.
Regardless of talents, I am certain that all great players achieved consistencies through practice sessions with strict routines --- until the swing become their second natures. I agreed that you need to change your perspective and start developing routines for practice sessions. With lots of experience over the years, you frustration should not be too difficult to get rid of.