I don't think anyone can tell you what is "sufficient" for the DAT because there is so much information that is fair game. I am working through all 10 DAT Bootcamp exams making sure to read and do my best to understand all solutions. Additionally, I am working through all of DAT Destroyer. As
@orgoman22 says, "Think 30." I think that the best way to prepare for this beast is to work and understand as many problems and concepts as possible.