For most mere mortals, know your equipment and then seat time.
As others stated, know how to make your instruments do what you want, knowing they work well, then......seat time.
Way back when, it was, "40+ hours seat time in the glider you will compete in BEFORE the first contest day....that season".
This basically means the basics of flying "just sorta happens" so you can figure out where to go and when as well as watch for others.

If the basics of the ship are OK, then for most peeps, the minor gain of "prepping the ship" is nothing compared to the nut behind the stick.