I can't speak for Chad Videos, but I will let you know the the Organic Chemistry Odyssey is more of a teaching book, it is broken down into chapters so you can work on your areas of weakness, it is not a book that has to be completed in it's entirety, you use what you need and leave the rest. I have received emails and praises through the years from students who have used the Odyssey. When you say very weak, I am not sure exactly how weak you are? But whatever you do, do not take the DAT until you receitify any area of weakness. This is not a test you want to repeat.
Wishing you the best
#think30, Nancy