If you want to make a great score, I'd suggest knowing it all. Some people can pull 30s on the QR.
However, if math isn't your strong suit and you don't think you'll need a great QR score to bring up your AA, I don't think knowing everything is necessary. It's a pretty well known fact on this site that some schools don't really care about the QR score at all. That being said, I still wouldn't discount it! I really don't like math, but I still did spend a considerable amount of time studying for it.
I only really focused on tests 1-6 and did them multiple times. However, for the really hard probability problems, I just said, "To heck with that!" and didn't learn how to do them. I still made a 21, which I was very happy with.
Know your trig. Know other tricks about triangles.