Admittedly, I've not tried it which is why I'm curious. I would expect that it's good at explaining well-studied algorithms but anything that's following more-or-less bespoke business rules seems like a different beast.

Again, I could be wrong; e.g., a banking application might have certain regulations it needs to follow making non-computer-technical reasons for certain things to be done. That would be a good candidate for a "helpful" comment which would be reasonably AI-generated. (Although, perhaps not a good candidate for an LLM-generated application.) The example of "our specific business wants this for reasons" is one that I think LLMs would struggle with unless that's included in the context window. Of course, that's also possible; not sure if that is presumed.