Sure, good question! First, it's important to note that all AAMC materials are incredibly useful, since all of them show the unique way in which the AAMC asks questions, and the importance of paying careful attention to wording.
But I tend to agree with what you've heard (that the section banks are better for the sciences) for a few reasons:
- The Qpacks are largely taken from old AAMC tests. People who have taken the "old MCAT" will immediately notice that many Qpack passages come either from AAMC full-lengths (if you remember, they used to offer tests 3, 4, 5, and 7-11) or the AAMC Self-Assessments. If you've used these resources before, the passages are going to seem awfully familiar. If you haven't, they're perfectly good practice, but the idea that they were taken from the "old test" - with all of its differences from the new exam - can make some students feel like they aren't that representative.
- The section banks are really graph-heavy. I was actually surprised at the number of complex figure-reading and reasoning questions in the first half of the bio/biochem section bank. These are the exact type of question that you should be practicing. Now, not all section bank Qs are like this - a number of the biochem ones are kind of specific and knowledge-based - but the "feel" of the passages is still more "new MCAT" than the Qpacks.
- The section banks have psych/sociology. Arguably, this is the section that benefits most from AAMC practice. In any case, it contributes to the same theme as the above two points - that the Qpacks are good for getting a general feel for the AAMC, but the section banks are more applicable to the new exam.
Hope this helps! Good luck 🙂