The report, and whatever people remember. The method leaves with whoever applied it — and that’s why the next diagnostic starts almost from zero.
Why does the report age so fast?
Because it describes a state, and the operation changes. Six months on, half the conclusions still hold and nobody knows which half.
Is that the consultancy’s failing?
No. It’s the model: it sells applied judgment, and judgment isn’t a deliverable you install. What it can’t do is automate its own discovery, because manual discovery is what it bills for.
What does “the layer stays” mean?
That the structure built during the cycle stays queryable after it ends: the facts, the links, and the source of each. A new question doesn’t require a new contract.
The next diagnostic starting from zero isn’t market inefficiency. It’s the design of the product you bought.