This is just from my experience, and I certainly am not anyone of any authority, but maybe it will help someone out there.
I just took my test this past Friday.
I had under 3 weeks to study for it, so I didn't have time for World and some of the longer sources, too. I had to pick one to go with and try to stick with it. (other than World questions)
I started out with FA, was pretty consistent at 55%. And there I stayed...for 2 weeks! I was getting SOOO discouraged, miserable, just absolutely beside myself. My score just did not improve. And you know, it's pretty hard not to pay any attention to those scores. I felt like I wasn 't getting anywhere.
I read in several of the posts about Secrets being good, so I switched. SO GLAD I DID. I had noticed while doing the UW questions that i would have read it in FA, but I just couldn't remember what I had read. That's SO exasperting. I'm not saying FA is not good, it's just that I didn't have enough time to take it in. (I must be a really slow learner!!)
Anyway, I was just beside myself, and then I decided I was going to have to do something different. I read several different posts on SDN and got some great input.
The main thing I changed was that I started reading Secrets in the morn, then did the World questions in the afternoon/night ON THAT SUBJECT that I had studied in the morn. My scores jumped up to 65 to 70%, immediately. At first I thought that would not be an accurate representation of my true scores, but it seems that when I read about it, then applied what I had read to the questions, it helped me to remember it. This really helped me. My only regret is that I didn't start out studying like that, and also that I wasn't able to get all the questions done. I got about 90-93 percent of the questions in, and you really need to do them all, then go back over as many as you can. I really needed another week.
I could tell in the test that this method of study really helped me, b/c the subjects that I did like that, I was MUCH MUCH stronger in.
Also, it helps your psyche when you see those scores up, and that is half of it. Was for me, anyway. Not nearly as hard to study when you're seeing some results.
And as for those confusing tests on World that the OP is talking about, let me tell you, they are on the real thing, too. And, no, don't go back over the questions you've already done to get your percentage of accuracy, because the results will not be accurate if you've already seen it and know the answer ahead of time.
World is a great prep course. It's the same format -- same frustrating questions where there seemed like 3-4 good answers, but they just wanted one. But just keep doing those questions, believe me, and it will help you.
I feel lots more confident about this test than I did step 1, and I need a good score to make for a dismal score in that one.
Surely wish I had read SDN back when I started studying, it really helped me a lot.
Hope this helps someone. Good luck.