Most organisations buy a second opinion at exactly the wrong moment: after the decision has been taken, when what is really wanted is cover. The fee is spent, the report confirms the position, and everyone treats the exercise as a formality — which, by then, it is.

The cost you can see

A genuine challenge is not expensive relative to the decision it examines. It takes weeks rather than months, and the meaningful cost is rarely the fee. It is the delay, and the discomfort of having a competent outsider ask why the base case assumes what it assumes.

That discomfort is the product. If a review returns nothing that irritates anybody, it was not a review.

The cost you cannot

The alternative cost is invisible precisely because it is never incurred as a line item. It shows up as an acquisition that took four years to write down, a market entry defended long past the point of evidence, or a programme that nobody could stop because too many people had endorsed it. None of these appear as the cost of not having asked. They appear as bad luck.

What to ask for

A useful second opinion is narrow. Not is this a good idea, but which two assumptions is this case most sensitive to, and what would we need to observe to abandon it. That question can be answered properly in a fortnight. It also produces something that survives contact with a board, because it does not require the board to accept a wholesale alternative view — only to agree what would change its mind.

We would rather be asked before the decision than after it. The engagement is shorter, cheaper, and considerably more likely to matter.