A process can look complete on a diagram and still have one step left that determines the outcome.

That final step is what I mean by The Last Inch.

It is not literally an inch, and it is not only about parcel delivery. It is the point where strategy, design, policy or technology encounters actual use.

The plan is not the behaviour

A system designer can specify the intended path. The person using the system still has to understand it, choose it and be able to follow it in the environment in front of them.

That creates a set of questions I keep coming back to:

  • What does the process expect the person to know?
  • What is the path of least resistance?
  • What does the physical environment make easier or harder?
  • Where does responsibility become ambiguous?
  • What evidence would prove the explanation wrong?

Why I care about the handoff

Blaming the person is often tempting because the person is visible. The mechanism that shaped the behaviour can be less obvious.

That does not mean behaviour never matters. It means I want to understand the system before deciding where the failure sits.

The useful question

When a system keeps producing an outcome nobody intended, I want to know what happens in the last inch between designed and done.

That is usually where the interesting part starts.