I'm going through API right now, and the word is that it counts, but not for much. All of API is aparently worth less than the smallest portion of Primary. So, the word is, always do your best, but don't let it drive you crazy. If your passing, your doing it right, if your failing, your doing it wrong. It's not meant to be, "this guys smarter than this guy", it's "how well you can take in large amounts of info in a short time."
A big key is to study in groups. Another person or two will always be able to help explain a concept you don't get to well. The first thing they ask you when you fail a test is "Did you study in a group." Implying that that's the big idea.