This is interesting. I own several sketchbooks, and I'll have to admit that I don't often sketch in them; however, sometimes when I'm trying to test out something, I'll try the concept in my sketchbook first.
However, a year ago, or so, I was browsing through the mishmosh of my old sketchbooks, and I ran across a very abstract, surreal-type of drawing that I must have done years ago, and I figured that I would make an oil painting out of it. Now, I'm a painter of realism, so painting such an abstract subject is out of the ordinary for me.
I tweaked it a bit here and there, and painted from this crazy, odd-shaped jumble of abstract, surreal shapes, creating quite an unusual oil painting. I entered this oil painting in my art club's spring show a couple of years ago, and low and behold--it received a best of show!
So, do I like sketching in my sketchbook? You better believe I do!