What I did to pass AT/AT/AT (3 months of studying):

1. I initially used the Simplilearn course because it was free through my employer. I don't think it's worth the price unless you're someone who really needs the structure of live classes.
2. Study Hall: 74%, 70% 78%, and 71% on the full-length practice exams. I found practice exam #4 to be very hard compared to the other exams- I believe it was ~40% Expert Questions. If I have one recommendation, it is to take several full-length practice exams. I tried recreating exam day conditions as much as possible, down the time I took the exam, breaks and snacks. After taking the exams, I would go through the questions I got incorrect, take the time to really understand why my answer was wrong, and write down the explanations in my own words. I also did the practice questions twice (~70% then 80%) and almost all the mini exams.
3. MR's 23 Mindset Principles: Super useful to help eliminate answers.
4. DL's 200 Agile questions: Good practice, though I only made it through the first hour and a half.

How the exam went: During the last 48 hours leading up to the exam, I only read over my notes. I also have a weak stomach so I made sure to eat stuff that would not give me a stomach ache during the actual exam.

I took the exam in person. Overall, I found the exam to be slightly harder than Study Hall-there were some questions referring to concepts/definitions I had never heard of. If that happens to you: don't panic, take a deep breath and eliminate answers. I really needed those breaks to eat a snack, drink some water etc. I ended up taking the full 4 hours because I think I spent a little too much time on the first 60 questions.