Comment by lisper

My favorite metaphor: bridge and road maintenance. Every now and then you have to fix potholes and repaint the bridge. Sometimes in order to do this you have to close some lanes to traffic. If you don't do this, you will accrue more and more potholes, and the bridge will start to rust. The longer this goes on, the harder it becomes to fix. If you ignore the problem long enough, the bridge will collapse one day with very little warning.