After talking to a colleague about taking some sample tests (and finally getting over the nominal passing hump), I bit the bulket and paid for another prep course. This one is a bit broader, and covers many of the topics that seemed like surprises in the first test or two. I'm not completely finished this new course, but I think I'm going to do one more major section and then try another sample exam. I hope that it's a decent strategy. Things I've been weak in include Auto Scaling Groups and Cloud Formation, and while the first prep course gave an introduction this course has helped solidify things. The first course showed a quick picture of nested stacks, while the second does a hands on deployment, which helps a lot. I feel much more sure on many topics now, and there are questions I would have gotten in some of the earlier tests if I had taken the course earlier. I need a bit more hands on practice, but that will come soon.