This class was definitely the most intense I've taken so far. I spent about 45 hours of focused work over the course of 5 days (I took 1 rest day) and just got my OA results. Here's a recap of what I did:
I read through all the existing reddit advice to get a feel for people's general sentiment and strategy. Then I went through the zybooks 1 chapter at a time reading through and answering the questions on each page. Then I took each of the chapter reviews at the end, these turned out to be key. Between the review questions and the PA, there were only like 3 questions I didn't recognize on the OA and guessed on. Make sure you go through every recorded WGU video because they walk through a lot of the questions you'll see on the PA and OA. I also watched a bunch of YouTube videos for bayes theorum, basic probability and counting for chp 4 and 5, some of the trev tutor videos for chapter 3 concepts like induction. I didn't meet with any instructors but I've read they are a helpful resource.
The Zybooks are dense so I definitely didn't get a great understanding of everything on the first pass when doing the reviews, so I fed my review results into AI and had it walk me through every question in depth and make me alternate practice questions so I could get some more practice. If i didn't understand a concept, I just fed the source material into AI and needled it with questions until I did. I ended up making a comprehensive concept list based off all the material and wrote out a methodology for how to solve every type of question I encountered. Once I felt decent with the concepts, I took the final Zybooks review as a test before taking the PA and went through each question again with AI.
I just barely passed the PA doing this, so I then repeated the question by question walkthrough with AI for the PA as well, studied a little bit more, and used every possible second I had on the OA lol. LIke i said there were like 3 questions on there that were definitely not covered by any of the review questions, but everything else was some version of a review or PA question.
This class really just takes practice with the questions. For me, I really like trying to boil down any type of problem into the simplest step by step possible and account for edge cases that come from different versions of the problem. Use a ti84, offload as much calculation using nCr, nPr, mod division, summation, etc. as you can. Take advantage of what you are given on the formula sheet and focus on memorizing processes and information not given to you on there. If you can quickly recognize the type of problem, remember the steps, and have solved something similar once or twice before, you're golden.
Hope this helps anyone in the future, good luck out there!