If your delivery drivers have to do six deliveries a day, they’ll rush from the first moment. They’ll be super efficient at easily measurable metrics. They’ll cut a few corners.

If they only have to make five deliveries, you can ask them to spend that ‘down’ time doing things your customers will actually remember. They can invest in less easily measurable metrics. Instead of cutting corners, they’ll embrace them.

Systems with slack are more resilient. The few extra minutes of time aren’t wasted, the same way that a bike helmet isn’t wasted if you don’t have a crash today. That buffer will save the day, sooner or later.

One thunderstorm can cripple the air traffic system for six major cities, because each plane is stacked so efficiently that the ripple cascades, leading to failure and cancellations. In the old days, when efficiency was measured over a longer term, there was enough buffer to absorb a bump like that.

The mistake happens when we over-index on the easily measured short-term wins and forget to account for the costs of system failure.

Competitive environments push profit seekers to reduce slack and to play a short-term game. If your organization hits the wall, the market will survive, because we have other options. But that doesn’t mean you will survive.

Slack is actually a bargain.