When demand fluctuates, the costs of meeting it can easily go up and its quality can quickly go down. Some public services seem designed to maximise peak demand, others need to be ready to respond to demand which fluctuates for external reasons. That’s an aspect of service design which is often overlooked: the need to optimise individual interactions and the system supporting them is much more obvious than the opportunity to influence (and in some cases directly manage) the pattern of activity over time. So it’s worth reflecting on the scope for improving both service quality and efficiency by better managing the flow of demand.