How gave you been scoring on the practice exams youve taken?
Have you done many practice problems? Do you have the destroyer?
You can probably complete the DAT destroyer in 2.5 days. If you do it through completely twice in 5 days, you can spend your 6th day making study sheets on the problems. Common bio themes, and then the major repetitive gen chem math based problems, with the steps on how to solve each one. If you learn that study sheet, once you see that chem problem, the steps to solve should click so you can immediately tackle it efficiently. The more familiar you become with the problems and repetitive manner in which theyre presented to you, you will increase in speed while at the same time learning the material.
You can perhaps decide that when you see a problem you had practiced before, and know it will take a while you might want to MARK it, and leave it untill later. I wouldn't recommend spending one minute, and then skipping it and forgetting that minutes worth of work you had done. Also, the reverse to this is you may know it will take a little while to solve the problem because you know how the problem works, but on the same note you will be likely to solve this problem and get a better grade because of it.
As mentioned before, most of the math problems are figure out the solution in terms of the formula, not the numerical answer.
i.e. you woiuld see "A) 2x4/2" as opposed to "A) 4"
The best you can do is take as many timed practice tests and work on balancing speed/efficiency. By my 12th practice QR my speed had drastically increased.