I think it gets harder at book 5 bc of all the risk management/hedging but then better at book 6.
Book 1 is a soft ball. In gereral I would say slightly harder on the back end. You’re all more sick of it so it gets harder to deal with. I’m thinking of skipping the last half of book 5, risk mgt, and go to 6, then come back.
But i think once done with the books, EOCs too, and you’re at doing practice/exam problems, real learning begins.