My TBR pile is insane right now. And I keep buying more books. It's not too smart.
Mine used to be like that. I got rid of a few hundred books a couple of years ago, and also some actual shelves. Mostly I collect e-books.
I try not to but if I run out of room then I have to do it until I get more shelves/space.
I shelve my books however they fit. The dog might eat them otherwise. :)
I do this all the time. The alternative would be just too bad, I'd have to give up most of my books. :(
My shelves were like that recently but I painted my bookshelf so I took all the books off and then weeded through them to either keep or giveaway. So now the books are only one level deep.