Stop when you feel like it, just like any other verification method. You don’t really prove that there are no problems with software development, it’s more of a “try to think of any problem you can and do your best to make sure it doesn’t have any of those problems” plus “just run it a lot and fix any problems that come up”.

An LLM is just another approach to finding potential problems. And it will eventually say everything looks good, though not because everything is good but because that happens in its training data and eventually that will become the best correlated tokens (assuming it doesn’t get stuck flipping between two or more sides of a debated issue).