Just my opinion...but maybe this comes from a different perspective than you normally hear.
I was pitcher. See I was fat kid that got tall. But I could throw it. So I was labeled as a pitcher early.
Hitting instruction in my day ranged from "Keep your eye on the ball" (Still good advice) to "Keep your elbow up", "Hit down on the ball"...anyway..
I started studying the swing before my son was born, when I was asked to help coach some older guys.
I've studied Epstein, I've read Lau, you name it I'e probably researched it.
By the time my son was born, and showed an early love for the game, I used him as my guinea pig.
I do NOT consider myself an expert. I did not invent the wheel and I don't get paid to claim I did.
I simply look at / observe the swings of the best hitters in the game, and try to find out what things they all have in common.
1. They don't hit down on the ball.
2. They don't swing level to the ground.
3. They don't generate the majority of their power with their hands.
4. They stay back as long as they can, even at contact.
Every player has a natural swing. I think that the majority of these swings can be modified to be what most would consider a high level swing. To me..again my lowly opinion...
Everything a hitter does before they get loaded and then to the contact position is simply personal style...window dressing.
High hands, low hands, a wiggle, a waggle, whatever it may be. If they are getting to the right place at contact, whatever works for them.
Of course I could be DEAD wrong, but I'm starting to see a lot of cookie cutter swings. The open stance and step in model tends to have gained favor in last year or so. I see coaches who preach this and that, but then see their best hitters do neither.
Again, my lowly opinion?
1. Use the big muscles to coil and generate the power.
2. Try to meet the pitch level to the angle it's coming in..."that mean's it's coming down off a mound in most cases".
3. Hitting the ball in the air...only pitchers want ground balls.
4. Letting the ball get deep. This allows a hitter to wait longer to choose what pitch he wants to hit.
5. Keeping your weight or shift back as long as possible.
Of course that's just my lowly opinion.
