At other times, the reverse is true and responsiveness really is more important than efficiency, as in the case of graffiti. It might seem that the most efficient thing would be to treat graffiti like snow—take whatever resources we have for repainting, and have them work the city, street by street, systematically. But if a stop sign gets tagged with graffiti, leaving it there even for a couple days might motivate someone to tag something else nearby. Whether it’s a gang sign or a cartoon bunny, what shows up on Falcon Street may soon be copied on Walnut, and the longer it’s there,
