Right, but the comparison isn't perfect here because wall height is linear in the analogy, but searching for exploits in an existing piece of code reaches a poi

Right, but the comparison isn't perfect here because wall height is linear in the analogy, but searching for exploits in an existing piece of code reaches a point where either there are none left to find, or finding the next exploit would take years. That's the stalemate point I referred to. (Any high-stakes project may end up having its own "red team" agent/s running 24/7 too.)