I also think it's good to add that you should avoid the weight getting up on the toes. This causes the spine angle to rise and the pivot to stall. Put it this way, if I were to take my stance w/o a club and then get up on both of my tippy toes and then try to pivot back and thru, I'm going to have a hard time doing so. Also, it will be difficult to balance myself and I subconsciously straighten the spine angle in order to do so. OTOH, if I get the weight more in the middle of the arches of my feet, I can pivot back and thru more freely and efficiently and maintain my balance.
One of the biggest helps to my game and ballstriking was understanding that the weight should be about in the middle of the arches of your feet and to avoid getting it up on the toes. I guess some golfers with very circular hand delivery paths can get away with getting up on their toes so they won't hit 3 feet behind the ball. But for most, the back heel needs to be 'pulled' off the ground from the momentum of the swing, not 'lifted' off the ground by getting the weight up on the toes. Major improvements to my impact positions happened once I understood this.
3JACK
