I'm bad with it, journal articles everywhere and I have a tendency to print chapters/papers several times in order to annotate them.
I can't read off the screen. I always miss stuff. Not to mention I tend(ed) to grab papers and read them/scribble on them for an hour before bed quite frequently.
I do feel a bit guilty when I see all that paper sometimes though. Then I just shove it under the bed, innit.