Steph, your experience sounds similar to mine; mostly, it was an affirmation of my instincts. For example, when she asked me to bring out my makeup (which I hadn't worn for the draping) she said, "Wow, those colours are perfect for you." And it turns out that the colours I generally feel drawn to (to wear) really were the ones that best suited me. But one bonus was being reminded that I could also wear others that had somehow slipped past my radar. Not because I didn't like them, but I just never thought of them.
She had also asked me to bring along a few items I owned that were "questionable" in my mind. So I did. One was a patterned dress with navy, green, and mustard yellow. Although it really fit mostly in the autumn palette, the dress works on me because of the navy, which is dominant. There isn't as much of the mustard, and it works nicely with my hair. Another top I brought (also a pattern) had bright, clear red, a vivid pink, orange, and a yellowy cream in it. It also manages to look good on me—when I have a bit of a tan, that is. Not without. But the red and the pink sort of cancel the orange and yellow and altogether it works.
I liked that reminder that we don't have to stick rigidly to the "system," but can use our own best instincts once we've trained our eyes.