Every finance team has one. The person who knows how the reconciliation actually works, why the third tab exists, and which supplier codes are wrong in the ledger but right in practice.
They are usually excellent. That is the problem. Because they are reliable, the dependency never surfaces as an issue , until the week they are unavailable, at which point it surfaces as a crisis.
The cost you can already see
Some of this is visible if you look. Month-end takes longer when they are on leave. Queries route to them regardless of who owns the task. Their holidays get scheduled around the close calendar rather than around their life, which is its own quiet cost.
The cost you cannot
- Constrained growth. Processes that live in one person's head do not scale. Winning a large contract creates a bottleneck rather than capacity.
- Unauditable logic. If nobody else can explain why a figure is calculated the way it is, you cannot assure it. That is a control weakness whether or not an auditor has raised it.
- Undetected drift. A single owner adapts the process continuously and reasonably. Over years it drifts a long way from what was designed, and nobody has a reference point to notice.
- Retention leverage in the wrong place. Nobody plans this, but a business that cannot close its books without one individual has quietly handed that individual a great deal of power.
What actually fixes it
Documentation alone does not. Process notes written under time pressure describe the happy path and omit the judgement, which is the part that matters. Six months later they are out of date and nobody trusts them.
What works is reducing the amount of judgement the process requires in the first place , standardising the inputs, removing the steps that exist to compensate for bad data upstream, and automating the mechanical work so that what remains is genuinely a decision rather than a habit.
The goal is not to document what the expert does. It is to build a process that does not need an expert to run it.
The person is then free to do the work you actually hired them for. In our experience they are the strongest advocate for the change, because they have wanted to take an uninterrupted week off for years.