I'm still trying to figure out how to produce a codebase using LLMs and end up as a expert in the system at the end of it while still coming out ahead. My hope is I can be more of an expert a bit faster than before, not less of an expert a lot faster.
It feels within reach to me as long as there's frequent periods of coming to a complete understanding of the code that's been produced and reshaping it to reduce complexity. As well as strong technical guidance as input to the LLM to begin with.
I think there's still a lot of learning to do about how to use these things. For example, I've tried LLM-heavy things in lua, C, and C#. The LLM was great at producing stuff that works (at first) in lua, but lua was miserable and the code ended up a huge mess that I can't be bothered to become an expert in. The LLM was really tripped up on C and I didn't make it that far, I didn't want to watch it fight the compiler so hard. C# has been great, the LLM is reasonably effective and I have an easy time consuming and reshaping the LLM code.
I've always liked static type systems but I like them even more now, in part because they help the LLM produce better code, but mostly because they make it a lot easier to keep up to speed on code that was just produced, or to simplify it.