For me personally, iterating is huge. You can't arrive at a hugely complex system in one shot. I think of the LLM as someone I'm running software engineering "experiments" with. As requirements become clearer, I discuss with it more and more and over time I'll gain a stronger understanding of the problem and possible solutions.

You'll also discover over time which systems the AI can handle fine on its own and which abstractions and systems it just has no ideas on how to design. Often I find I have no idea how to design those too. It's then useful to try different designs, test tradeoffs and refactor aggressively if needed.