That's also how you get security nightmares.

The way I use LLM's is that I design main data structures, function interfaces etc. and ask LLM's to fill them. Also test cases and assertions.

This. I find bringing in the LLM when there is a good structure already in place is better. I also use it sparingly, asking it for very specific things. Write me tests for this, or create me a function that does this or that. Review this, extend that etc.