Hi Danzig, I agree with the overall point that Mike made above, you can always expect to see something unexpected on the GMAT. It's impossible to prepare for absolutely everything, and in fact there is tremendous value in determining how you deal with a question you've never seen before based solely on the information in front of you. I'd say: embrace it! You know how to solve these questions, even if some of them look novel. Once you're consistently getting the score you want, you're ready. Your actual score will be similar to what you've been getting in practice, with the element of how well you perform on test day. That's why I strongly recommend being well rested and focused on test day. Your goal is to perform as well as you possibly can, even if there's the occasional question you've never dealt with before.
Hope this helps!
-Ron
Hope this helps!
-Ron