Research is addictive. You concentrate in a way that blocks out other things. And you do not want to break that concentration. As my current contract dries up, I suddenly find myself with far more time for research. I start to resent the time I have to put it aside for teaching activities. There is a taste for research, and if one teaches too much, it can dry up. But once it reawakens, it reasserts itself and the tables are turned.