Hi!
So for me, I studied for about 2 months. I memorized about 500? if not more brand names - made sure to memorize different brand names for the same drug (for different dosage forms) with their indications, and I went through the Rxprep course book 3 times I think - once fully (except non-drug chapters) and twice with focus on main chapters. I might have taken longer to study because I have never practiced as a pharmacist since graduating from pharmacy school because I continued schooling, and after that, I was in the process of moving so didn't have the chance to work as a pharmacist. I also bought the test bank on Rxprep. I bought secrets to CPJE packet, which I used 1 week before the exam to just summarize what I had learned.
I hope this is helpful! I really think having memorized many many brand names was really helpful.