I took mine on July 3rd after studying for 2 weeks, 5 days a week, for 8 hours each day.
I just used the Mastery App and some released ADA exams from '98. Felt good about the test, but I guess we'll see if I passed.
Frankly, if you're pushing hard, you can study and be done in a couple weeks. Don't use too much stuff though. If you're into just doing questions, I'd go through the decks once and review the info on the cards. It's a lot, but it helps. Mastery App is similar, but less in depth.
The most money for me was the practice exam I did from the ADA. Some questions were exact repeats off of the test, and I wouldn't have known them had I not taken that exam as a practice. The best thing you can do IMO is take real, old, exams from the ADA.
Good luck!
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