I found destroyer to be exremely helpful. Yes, the first time I tried to do the problems, it was terrifying. But here's what helped me deal with destroyer problems:
For G-Chem:
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-I quickly went over the 12 chapters in KAPLAN.
-After getting down the basics, I started on solving problems in destroyer.
-I marked the problems I couldn't solve.
- After going through all questions, I went back and did them all over again, this time paying more attention to the questions I marked.
**I did all the G-chem problems 4 times.
After completing that, the stuff on the actual DAT was a piece of cake.
DAT Score: 24
O-chem:
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Don't even waste time reading the KAPLAN book. The reactions mentioned in KAPLAN are hardly a fraction of all the reactions you need to know in order to score above 20 on the real test.
Personally, I went back to my notes. I memorized all the reactions. It took me a good 2-3 weeks.
After getting down all the reaction schemes, I came back to destroyer.
Again, I used the same strategy. I did all the questions 4 times, each time paying more attention to the questions I missed last time.
DAT Score: 23
Bio:
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Again, KAPLAN only gives you the general idea; it does not by any means provide you with the details you need to get a decent score on the real test. Nevertheless that was the only resource I used. Then I started doing destroyer. Then I read the answers to each question throughly. Sometimes I googled the topics I didn't understand.
DAT Score: 21
Overall, I think destroyer might be a bit harder than the real test. But if you get those questions down, then the real test should be easy.
Hope this helps...
Best of luck to you!!