Hi,
I believe there is not just a single way to approach the PMPrepCast Exam Simulator; it very much depends on the way you learn and what makes you more comfortable with.
I almost used all full exam simulations only, except for a few quizzes I used to practice when I didn't have time for a full exam. I found them also useful to improve on my weakest areas. But all in all I preferred to go for a full exam any time I could.
I understand your concern about getting familiar with questions you already answered; however, what I noticed was that I didn't remember the right answer itself, but rather the reasoning that led me to the right answer. And to me this was the most important thing, because memory can trick you on the exam day, but if you can follow the appropriate reasoning, you will still answer the question correctly.
Hope this helps,
Gabriella