I began practising guitar 2 years ago @ 62 to keep my mind challenged. Using the practice of a slow motion, problem solving approach is brilliant advice that I am definitely going to enact.
Yes, practice may not make you perfect but then, practicing "perfection" makes you perfect!!. I recall a few phrases from 30 years ago while I was working on my typing classes on a typewriter and the phrase goes like this.... 1. "Accuracy first and speed will take care of itself" 2. "Slow and steady wins the race" 3. Practice makes you perfect" (as you put it, if you practice"wrong learning" then, that "wrong learning" becomes perfect).