"I'm quicker when I'm pushed"

Some people will say that they need the pressure. If they leave with time to spare they dawdle, and if they leave late they move. The dash gets them out of the door. Without it, nothing would.

There's something in this. A deadline concentrates the mind, and the fast walk is a fast walk. But look at what the pressure does to the estimate, because that's where it does its damage.

Buehler, Griffin and Heather MacDonald tested what happens to time predictions when people have a reason to want the task done quickly. In one study they looked at people filing their tax returns. Those who were expecting a refund, and so had a reason to want the return in early, predicted they'd finish sooner than the others did. They were also more wrong. Their predictions were more optimistic and their actual filing times weren't correspondingly earlier. In a laboratory version, an incentive for finishing early made people's predictions more optimistic, made them attend more to their plans, and made them attend less to how long similar things had taken before.

So wanting to be quick makes you believe you'll be quick. It doesn't make you quick. The person who leaves at ten to nine because they're sure they can do the walk in ten minutes has been made more confident by the pressure and not more able. Torleif Halkjelsvik and Magne Jørgensen, reviewing the whole field of time prediction in 2012, list incentives for speed among the things that push estimates in the optimistic direction.

I'd add what the dash does to the thing you arrive at, and this is my own reasoning. You get to the meeting with your heart going, slightly damp, holding the wrong notebook. It takes several minutes to settle. You've missed the first item and you'll never fully catch up. At Dan and Ellie's, you arrive apologising and stay apologetic for the first half hour, and you spend the evening a little behind everyone else. The pressure got you there. It didn't get you there in any state to be useful.

And the belief that you need pressure is worth testing on the cases where you don't use it. You made the flight last summer. You were at the airport two hours early like everyone else. Nobody pushed you. You looked at the time the gate closed, worked backwards, and left when the arithmetic said. It wasn't pressure that did that. It was treating the time as fixed.

If you genuinely find that a spare twenty minutes turns into forty minutes of dawdling, the answer is in chapter 17, and it's to leave when the alarm says and dawdle at the other end. The dawdling can happen anywhere. It's only harmful when it happens between you and the door.