I am a bit sceptical about about claims of completing exams in a short time. I don't doubt it's possible. I just question whether it's effective. I had my head in the books quite regularly over the whole period of my PPL and I immodestly consider myself pretty good at picking up new technical info from books. Some subjects are quick and easy and some more challenging. Of course, not every one finds the same exams easy. So don't expect all the exams to take the same period of time.
I found it necessary to get practical experience to give the theory some context.
There will be some topics you want to learn, rather than just pass. Hopefully, most of them.