The evidence here is thinner than the confident commentary suggests, and the honest position is a shrug with a direction of travel. Notice how rarely anyone is argued out of the round number, and how often they are simply moved past it by a change in circumstance. A pattern this consistent is not a character flaw. It is a design feature, and design features can be worked with. Put a number on restraint and it becomes a target; put a target on it and the number stops meaning what it meant.
Why it persists
If you want to see restraint at work, watch a queue form where there is no reason for one. The point is not that people are foolish. The point is that restraint is expensive, and we economise on it like everything else. Ask most people why they did what they did and they will give you a reason; ask them again a week later and the reason will have quietly changed. The textbook treats restraint as a preference to be revealed. In practice it is a story we tell ourselves after the fact.
