I'm a big fan of not finishing books.
Oh, I finish most of them I begin. But when a book just isn't working for me, I lay it aside.
It doesn't mean the book is bad. Or that the author is wrong. It just means that, well, it's not working.
This does something good for me: it allows me to read more than I would otherwise.
Those who feel an overwhelming need to finish every book they start will avoid ones that look hard, marginally uninteresting, whatever.
My philosophy allows me to begin even those I'm not sure about. Because I know I don't have the heavy burden of finishing the book.
This philosophy has to be coupled with at least a modicum of persistence: some books don't yield their treasures easily. If you give up at the slightest intellectual resistance, you'll never complete anything of value.
But allowing oneself the freedom to lay aside a work that's just not of value to you at the moment will help your learning, help your studies, and give you the freedom to roam further than you might otherwise.