I used to do this too, ordering a big box of books from syllabus of prestigious universities at a level that was often way beyond me. I usually flipped through

I used to do this too, ordering a big box of books from syllabus of prestigious universities at a level that was often way beyond me. I usually flipped through them, and picked up a few things, but in the end I realized I had to really understand linear algebra, or number theory, or whatever, to really grok what was going on. Now I knew I needed these prerequisites and why, not that someone just told me so. This motivated me a lot more to get through (or nail) the prerequisites.