>> No matter how precisely you specify your epic, if the model will find something that contradicts your knowledge/intent, there are good chances it'll get confused and make subtle errors, and you won't realize until much later.

True! hence the need for someone to review the final spec output and own it as their own output. I have also found LLM to be better at debugging and solving 'a' specific problem, which I believe is due to output's surface area to be reviewed is lesser in comparison.