i think that works on every section except the PAT....kaplan basically gives almost the same books to MCATers as well as DATers...so yeah...the main point is to study hard...you could study for the mcat lazily and still do poorly on the DAT...
It may be true that studying for the MCAT will aid you in scoring exeptionally well on the DAT, but I believe it is like saying that earning $100,000 will help you buy a Pinto -- there is a much easier way to do well on the DAT!
The DAT tests on generic and simple questions when compared with the MCAT. In other words, studying the MCAT to prepare for the DAT is going *way* overboard. Why memorize and learn trivial details that aren't required of you? If obtaining a high score is your only goal, it is completely unecessary to study MCAT materials. It's overkill and you might just memorize so much unecessary (in DAT terms) junk that you'll forget some of the basics.
For example, in most cases the DAT wants you to know what happens in the mitochondria, not the nitty-gritty of the cycles themselves. Why clutter your mind?
22 and 23 aren't hard to achieve just by using the Kaplan DAT book.
What many may not know is that the MCAT -- for the most part -- tests only the basics of the sciences, and not the details; the details are given in the passages. Knowing the specifics will definitely help you and give you that psychological edge/advantage which is oh-so important!