All of my King books are paperback. I try to take good care of them as I'm reading them so they don't split on the spine or get worn too much.
Once read, they are stored so they maintain their condition fairly well.
I have noticed some of his recent novels seem to be bound differently or something, because they don't seem to crease on the spine as easily.
I just finished 11/22/63 in paperback, and it was that way.
The spine seemed almost flexible.
My paperback looks almost unused, even after reading the entire book, save for some newsprint on the pages.
Whatever they're doing different, if they are, I like it.