Value shows up in the P&L or it did not happen.
The most common way AI work fails inside a company is not technical. It is a decision, made early and defended forever, not to attach the work to a number. Once that decision is taken, the only thing left to judge the project by is activity, and there is always more activity: it never runs out.
A number is a limit, which is why it is unpopular. It rules out claiming success later on vaguer grounds. It means someone has to say, at the start, what the fix is worth, and someone else has to agree that it is worth doing at that price. That is uncomfortable in exactly the way that useful conversations are uncomfortable.
The practical test. If the system works exactly as designed, the effect should be visible in the profit and loss statement twelve months later, without anyone having to argue the case for it. When the honest answer is that it would not be visible, the project was never really about the P&L, and it is worth saying so before the money is spent.