The test actually does a pretty good job of spreading questions out among all the covered topics. Even if a particular test administration is heavy on a particular topic you are still rewarded handsomely for thoroughness in preparation.
There is one thing that I remember since it showed up twice in a Top Score Pro test and twice on my DAT. Remember that the halogen substituents are deactivating ortho-para directors, this is an exception that you needed to know in order to correctly answer two questions on my test. 2 questions are a lot on a test like the DAT, so there was a very high emphasis on knowing this fact. It is not asked directly but it is asked in different ways that need you to understand the implications of this exception. There is no gaurantee that it will appear on your test but it doesn't hurt to remember this.