Once a week or so, I buy some music. It needs tagging and cuepointing and all kinds of preparation before I can play it, so I have to listen to it with Traktor. And if I'm going to listen to it, why not mix it? I mean, I've been dying to do just that *all week*...
Warning: I've usually never mixed any of the tracks before. They rarely all go together. Sometimes I might do something silly like loop a phrase for five minutes.