" We fail to build slack because we focus on what must be done now and do not think enough about all the things that can arise in the future. [...] What should you do? Should you leave spaces open in your schedule...just in case something unexpected comes up...? In effect, yes. That's what you do when you allocate forty minutes to drive somewhere a half hour away...When you face scarcity, slack is a necessity. "

― Sendhil Mullainathan , Scarcity: Why Having Too Little Means So Much