I admit, I will often read the ends of books ahead of the game. But I find I only do that for books that have me so completely engrossed in the story that I get very anxious and stressed out. I find that if I read the end, I can let all that go knowing where things end up. And then I can really enjoy the journey to get there.
If it’s a book that I feel only so-so about and don’t really care about, then I don’t feel that anxiety and don’t really care where things end up.