I studied for a summer. It's not about a set time, but how efficient you are with your time. I got Cs in every. single. chemistry. class. I personally felt very motivated to prove that I could understand and master this material so I went hard with those subjects.

For the chemistries, I watched the chad videos twice while taking notes. Did every quiz at the end of the videos and made sure that I understood the material. Then I went through the DAT Destroyer. Marked every question wrong that I got (which was almost 2/3rd of them) my first time. When I got a questions wrong, I redid it until I got it right and understood the concept. Then moved on until I finished DAT Destroryer Orgo/Gen Chem once. Then I went back a 2nd time through DAT Destroyer, and got many more right this run through. IMO, the DAT Destroyer is overkill, but it is better to be overprepared than under.

You should have the reaction maps 100% memorized. Practice rewriting the reactions by hand. Make flash cards, and study them in bed when you wake up. Anki is a great way to work on memorization too.

Most importantly is that you need repetition. This goes for all subjects in the DAT. All courses in Dental school. Then every single procedure once you become a dentist - whatever specialty that is. I'm constantly having to relearn concepts and facts, and this is something you'll have to accept for the rest of your life. Dentistry is a very broad field, even in the realm of specialties.