Sure thing! I'll just go through my entire study plan though for anyone asking in the future, as I probably won't remember much later
QR: 340, RC: 360, Bio: 400, Chem: 400, OChem: 360, Physics: 350, TS: 400, AA: 370
To answer your questions specifically first: I only used the destroyer for some of bio and ochem. I found it helpful for bio (in the sense that it provides more random information that may or may not show up on the test), but it was definitely more difficult than the real test. For ochem, what was awesome about it is that the authors got back to me in 24 hours when I was confused about one of the questions, but I didn't do all of ochem questions on it. If I were to write the test again, I would go through all of ochem, physics and math questions for sure, because I think I would've done better if were able to do so. But again, I didn't, so I can't tell for sure.
I do think Kaplan and Barron's cover just about all you need for bio. But OAT destroyer lets your practice so it would be nice to do it if you have time.
Personally, I found that GChem and Ochem were easier than Kaplan's practice, and on par with ADA's practice. As for physics, although most of it was similar to Cracking the OAT questions, there were a few difficult questions that were more similar Kaplan's physics, and the amount of calculations really messed me up. Honestly, you just need to practice physics A LOT and that's why OAT destroyer would probably come in handy. I barely practiced physics.
On to my full study schedule:
Physics and math have always been my strongest subjects (as in, always got A's on them throughout high school and intro classes in university with barely any studying), so I didn't spend too much time on them. However, it's been 10 years since I've last done them. I've always gotten C+'s/B-'s on chem and ochem - again, 10 years ago, so I spent the most amount of time on them. My background is in cell and molecular bio and almost minored in psych, I got adequate grades in bio (B range), straight A's in psych, and for the past 4 years I've been doing research at a supplement company, and I just did Anatomy and Physiology a few months ago (and got A's), so bio seemed quite familiar except for taxonomy. Basically, I had to relearn chem, ochem, math and physics, and maybe parts of bio.
I started ~3 months before test day with Math. Kaplan was ridiculous and made no sense, so I completely relied on Chad's videos and quizzes. I think the reason I didn't do so well on it is because I didn't have time to do any more Math practice before the test, and I'm already quite rusty on it as is. Also, the online calculator SUCKS and lagged, didn't realize until halfway through the test that I could use the number pad, but it only worked for numbers not division/multiplication/addition/subtraction symbols. Time ran out without me noticing as I was reading question 37. I would have done better had I been able to spend time on the OAT destroyer Math questions, after all, there are barely any concepts to 'memeorize' in math, you just need to practice practice practice.
About three weeks or so later, I started doing Bio. I had to get through an English course in the meantime hence the hiatus. I only did half of it in about 10 days. At the time, I relied primarily on Kaplan's online course - I did the self paced one, and used the lectures, powerpoints, and textbook. I got back to it again about 2-3 weeks before test day to get through the other half, and as I was reviewing my notes, I felt that there is a lot of info missing (like plants, some details on cell division). I found Cliff's AP Bio online for free, but I prefer having a physical book. But I'm in Canada, and I couldn't find Cliff's in indigo/Chapters, but I found Barron's so I got that (amazon shipping would've taken at least a week, and I didn't have that time). I felt I needed both Barron's and Kaplan. Kaplan is more of a general, higher level coverage, whereas Barron's can get a little more specific on some intro topics, and it also has tons of questions. As I was going through Barron's and Kaplan's text and powerpoint (not lectures for the anatomy and physiology section), I did some OAT destroyer questions. I thought they were helpful, I didn't score myself as to not panic, but because I barely studied taxonomy (boring! and not many questions on it anyways!), I felt that the OAT destroyer filled some of my knowledge gaps. The real test wasn't as hard as the OAT destroyer for bio, Kaplan and Barrons were enough.
Around that time I did one of Kaplan's RC comprehension, scored 330, thought 'good enough' and that was the full extent of my RC prep.
Then, I spent about 2 weeks on Physics. I used primarily Princeton's Crack the OAT. Kaplan was way too confusing and frustrating for me. Then, about 2 weeks before test day I reviewed my notes, redid Crack the OAT questions, did some of Chad's quizzes (didn't watch the lectures), but they're very similar to Crack the OAT in difficulty. When I did Kaplan's diagnostic test two days before test day, it highlighted physics as a weak subject, so I spent the day before doing Kaplan's online physics quizzes, only to consistently score 270's - which only made me panic and I think contributed to me blanking (test anxiety) on test day. I certainly wish I had either done them earlier or not at all. For me, the physics section had a lot of calculation and not too many concept based questions, which made the time quite tight. I also felt most of the questions were similar to Cracking the OAT, and very few were on par with Kaplan's online course practice quizzes. Although after all, I got 350 and I attribute that to really understanding the topics due to Crack the OAT. I don't think much of Kaplan's quizz review 'made it in my head' because I was panicking and barely able to register the information. I didn't have time to work on the OAT Destroyer for that section. In short, I scored 350 solely because of Crack the OAT, which isn't a bad score. I think if I had spent more time really trying to understand Kaplan and did all the OAT destroyer questions, I would've scored 400.
About 2 months before test day, I did General chem. I only did Kaplan's text book and questions, it took me a week. Then about 1.5 weeks into test day, I spent about 2 days reviewing my notes, and doing Kaplan's online chemistry quizzes. I thought those were really helpful. I didn't have any time to even look at Oat destroyer for chem.
Around 1.5 months before test day, I spent three weeks on Ochem. I used Kaplan's text book and book questions, as well as Chad's videos. I hate ochem. About 1 week to test day, I started reviewing ochem, lots of crying ensued. Spent some time on Ochem odyssey (supplement to OAT destroyer, because I know I suck at Ochem), but I didn't even make it to the equations sections as time was running out. I also did all of Kaplan's online quizzes (more crying), and I also found this awesome youtube channel that helped me understand a lot of the concepts, it's called "Professor Dave Explains". He's adorable and pretty awesome. I spent a day going through all his Ochem videos and taking notes.
About 2 weeks to test day, I found ADA's online practice test. I was doing a few random questions, looking up the answers as I go through them, try to understand why those answers look like that. Nothing serious or timed.
Two days before test day, I did Kaplan's diagnostic test, which I was supposed to do like the first day I signed up for the course but didn't see the point of highlighting 'everything' as my weak subject and causing me panic, since I haven't seen most of the material in 10 years. It highlighted physics as a weak subject, I spent the day before the test day doing physics quizzes and doing terrible on them until 6 pm, then started reviewing ALL of my notes (about 200 pages) around 8 pm. Stayed up all night reviewing my notes, went to bed at 7 am, woke up at 10 am, wrote my test at noon. Bad idea, definitely contributed to slower thinking on the physics and math sections, therefore time running out, therefore panic, therefore blanking, and even slower thinking, resulting in a terrible positive feedback loop.
tldr:
Biology: Kaplan text, powerpoint and quizzes + Barron's + OAT destroyer (even just a few questions here and there) are awesome, got 400.
Chemistry: All I needed was Kaplan's text, powerpoint and quizzes, got 400.
Organic Chemistry: Professor Dave Explains (youtube channel) + Kaplan's text, powerpoint, and quizzes + Chad's videos and quizzes got me 360. Would've done better if I did more OAT destroyer questions on it.
Physics: OAT Cracker (Princeton) + Chad's quizzes + Kaplan quizzes got me 350. Kaplan may have dropped my score because it scared me rather than helped. I don't think Chad's quizzes contributed much. May have done better if I did OAT destroyer questions.
QR: Chad's videos and quizzes got me 340. I may have done better had I done OAT destroyer questions, especially during the week leading up to the test.
RC: One Kaplan practice quiz, got 360. No idea what I could've done differently, maybe practice more?
. I'm in Canada too, I'd apply to Waterloo but they'd immediately go "nope" because my GPA isn't high enough. Good luck on your app! I'm sure you'd get in pretty much anywhere.