Having just taken step 1 and hitting Goljan really really hard, I feel that the most valuable part of his teaching is how accessible he makes seemingly difficult stuff. Take, for example, how he explains serum Fe, Ferretin, iron binding capacity... After hearing his lectures, you should really have a grasp on that and when they throw those concepts at you on the exam, they go from being "tough" questions that you really have to think through to becoming "gimmes."
The bottom line is, no matter how much you study and who you use, the tough questions are still going to be tough no matter how much Goljan, FA, Rapid Review, Qbank etc you do. It is impossible to know it all but Goljan definitely helps as do all of the resources people in this forum swear by.
I, for example, got a boat load of immuno questions which, to put it as gently as possible, completely sucked. I got beat up on them. And it wasnt just what type of hypersensitivity rxn, but rather a question stem that was slightly vague with three different signals that "seemed" right.
Another question I got was about a guy who ate puffer fish at a Japanese restaurant. They then asked what the mechanism of tetrodotoxin in Fugu (AKA puffer fish) is. FYI, its a Na channel blocker. There was really no way to know that but the idea was to see if you understood based on the numbness in his mouth that it had to function like a local anesthetic.
The point I'm trying to make is that you do your absolute best and try to reduce the possible right answers as much as possible. The best way to learn how to do that is Qbank and other practice Qs. Goljan will set you on the right path, but the practice questions help a ton too. Remember that you need to get the gimmes right and that happens by learning Goljan and first aid. The hard questions are going to be hard no matter what.... (i think im rambling)... Good Luck.
