Dealing with a huge number of textbooks
I went to college more than half a century ago. I accumulated and still have all (I think) of the books in math. But I never actually read any of those books front to back. They were used as a resource to make it possible to gain insight and to solve problems. Some of them were more useful on the insight part, of course.
But, to answer the question, one way to use the books is to let the lecture notes be your guide as to where you should focus within them. Use keywords from the lecture, along with the table of contents and the index to find the things you need to focus on.
Textbooks aren't novels. They provide the outline of a field and, hopefully, plenty of useful (hard) exercises to build skill. With enough hard work, insight may come.
Read textbooks in &quot;snippets&quot;, stopping frequently to think about what you have read and find associated exercises to solidify the ideas.
This is especially true for the later chapters. It may be necessary to do more, such as re-reading, for the early parts, since you probably start out with very little skill. But the exercises may be more important than the text itself.