On occasion, I borrow a book without realizing that it's a spin off to a series that I have not yet read, or I start reading and dislike a book. In that case, I always return it right away,thinking of the other patrons on the hold list. Also, I can read a book in one weekend day, and I am thinking I am not alone.
And I, too, put a book on multiple hold lists and get it from wherever it becomes available first.
So far, the longest I have waited for a book was 3-4 weeks. If I desperately wanted to read it, I'd just buy it, but my TBR pile is sky high and my Kindle chock full with titles that wait to be read.