I am a tournament Scrabble player and the state of the art for studying words is spaced repetition. You quiz on "alphagrams", like ABEISTT, and after a few times you just see BATISTE BISTATE. There are at least 80K words between 2 and 8 letters long though, so it does take many hundreds or thousands of hours to learn them all well. I have very poor studying discipline so I have my own methods of studying that don't use spaced repetition, instead I just study all the words periodically and focus on the harder ones. But I don't know them as well, and for the words I did spaced repetition on more than 15 years ago I can still recall those immediately.
No - it's more efficient to just study a single permutation (we call it an alphagram -- the alphabetized letters on your rack). Then, when you are playing, just sort your rack alphabetically and watch spaced repetition at work.
