Hi, Yeoman.
I prefer to work through one project before moving onto another, for similar reasons to dustinzgirl. It's very tempting to go with whatever has the momentum on the day, though; there's nothing more disheartening than sitting in front of a blank screen/page, particularly when you feel you could be moving forward on something else.
As far as I can, I try to compromise; concentrate on writing one piece while editing or planning out another. That tends to work for me, but as others have said it's different for each person.
