I really like David’s use of “Admin” lists, which he mentions in part two of his fantastic OmniFocus Ninja Tricks screencast series. I see each of my OmniFocus folders as life compartments—areas of interest. Each folder contains goals (projects) and single action lists (overhead). Admin is a good, concise label for overhead, I think.
Conceptually I like the idea of maximizing goals and minimizing overhead. In other words—and, at times, idealistically—I put priority on forward thinking over reactive thinking.
Segregating overhead from goals is a critical first step. I’m putting Admin lists in each of my folders so that it's clearer how much overhead I have in each of my life compartments.