I only did the Apprentice steps, and recently finished posting them here. I got a lot out of doing it, probably more than I would have if I had just read the book on my own. So much that I am considering picking another card and doing it again. I'm really not "ready" to go on to the Adept stage because there are so many cards I haven't relearned yet.
There really are 21 ways to get into a card, especially if you go blank when you see the card, and you will learn them. A lot of them build on one another. So one of the things you will get out of this study is a quiver of arrows to use when you are reading, and most of them won't involve you running to your favorite book.
But she does have you do book meanings as well, and that step teaches you how to use a book when you are totally blank.
Your question was how has it changed how I read the cards. Right now I'm reading for myself, and trying to relearn what I used to know several years ago. It made me a lot more confident.