I always read 3 books at a time -- I don't know why do that either. It sort of annoys me.
Three at a time would be small for me. I am often close to 12.
I don't finish all the books I read. They are almost all non-fiction, so if I did read the ending, it doesn't make much of a difference.
I read what is interesting and stop when I stop finding it interesting.
Accept the past. Live for the present. Look forward to the future. Robot Fusion
"As our island of knowledge grows, so does the shore of our ignorance." John Wheeler
"[A] scientist looking at nonscientific problems is just as dumb as the next guy." Richard Feynman
"[P]etabytes of  data is not the same thing as understanding emergent mechanisms and structures." Jim Crutchfield
I usually start at the beginning, and finish normally... sometimes I even take time to read it all in one sitting regardless of length. If I don't finish it, I usually just read a synopsis somewhere else and get the gist of the course of events.
I am an absolute devourer of books I'm interested in (i.e. all the books I read - I don't really leave books unfinished.) and can read whole paragraphs with a glance if I'm really in the thrall of the reading mania.
I read the end of books first so that when I give up part way through at least I know what happened!
I read it from the beginning to the end unless
a) it's a book with lots of pages
b) it's really good and
c) I cannot wait to the end
In these cases I read the end before I should.
I read from here and there, only those chapters that interests me.
I read fast. I call myself a storyline reader. I follow the storylines very closely and I am very bored of books that have too much details and poor storyline. After reading a book, I cannot remember the details but I always remember the storyline. Same with the movies.
I love books which give you something to think about and in which you can guess the outcome. I love the books where there is some big pattern to be figured out.
I hate reality based books and I never read them. I don't like horror either because of my habit of getting too involved with the books (same with the movies also).
I am quite fast reader maybe because of my storyline reading. The downside is that details escape my attention.
I have always loved reading. I read a lot when I was a child and I still read a lot. My favourite books are fantasy, fiction, historical fantasy, old fashioned detective stories and MBTI books.