Unfortunately, with DRS being new, I don't think any review courses have much preparation materials for them yet. AICPA practice exam is probably about your best source for really knowing what a DRS will look like, but each one will still vary.
Given that you've tried 3 different review programs already, I'm going to hazard a guess that the review program isn't the problem in your case, and one or more of the ones that you have can be right for you to pass this exam. In your case, it seems like there's something with your approach to how you're learning and understanding the materials for this exam that's the problem, rather than the review course.
I know, “duh, that's why I'm posting here, thanks Captain Obvious”. My point is, I don't think you need to go spend more money on new materials (unless yours have all expired); I think that we need to look elsewhere for the issue.
My theory has always been that the key to SIMs is having a very solid understanding of the material, big-picture as well as details, whereas the MCQs require more recitation of minute details. So, if SIMs are your weak area (which they are for many people), my suggestion to you would be to try to focus more on the big picture. More practically, have you tried reading the books from any of your review materials? In my experience, it seems like the books are usually better at giving an A-to-Z, 360° view, big-picture perspective. So, if you've focused more on lectures and MCQs, then I'd strongly encourage you to try reading one of the books. Do it start-to-finish, without stopping in the middle for MCQs, since the goal is to be getting the big picture which is easier to do with continuity and not with breaks. Then after you finish reading the book, you can go to MCQs, practice SIMs, re-watch lectures over areas that you feel like you could use a refresher, etc. Personally I'm not a fan of what I've heard of Becker's books (though I've never held one so it's all here-say), so I'd recommend picking the book from Roger or NINJA instead of Becker, since I presume you have access to all 3; however, if you only have 1, go ahead with whichever one you have. Becker's still will probably work, just isn't as “nice” from what I've gathered – their focus is more on lectures so their book is a byproduct only.
If you've already read through the books start-to-finish before, then I'd still say focus on the big picture. The book is one way to do that, and it's a way that worked for me and I've seen work for others, but it's not the only way. SIMs require you to essentially take a story problem and figure out for yourself the 10 MCQs that relate to it and how to solve them, so it requires a bit more understanding of how things connect. Especially with exams like FAR and BEC, it can seem like they're a lot of disjointed information; if you can figure out how they connect and flow together, I think it will help you a LOT.
For the DRS more specifically, note that I finished before they were launched (by a couple years lol), so I'm shooting in the dark somewhat here. However, do you have any accounting work experience? Could you try to picture the problem in front of you as a task given to you at a new job by a boss who refuses to answer questions and see it as a real-world situation and figure it out that way? I think that's supposed to be the goal of the new DRS, but having never seen one myself, I don't know if that's really how they are or not. Just wondered if a real-life approach might help with them.
Good luck! Hopefully some of this general-SIM advice can help, even though DRSs specifically are a new thing that evreyone's still a little lost on.
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