Fair, my mistake.

I've built a lot with LLM's, my experience sort of but not really tracks that. I've had to course correct a few bad abstractions but the larger the code base becomes the better it seems to be at reusing things. Maybe this is because of types, or spec-first development (with OpenAPI), or black box integration testing - but also maybe not. But generally I have to think about the abstractions and let the LLM fill in the details with rare exception.

I built a web-OS, a graphical IDE, and a version control system to replace git, all in about 40,000 lines of highly abstracted Javascript. If you're thinking about how important it is to be able to maintain million-line codebases, I suspect you might have substituted a metric for the actual end goal.