My last job was on a fairly large typescript codebase (few hundred Klocs) which we started some time before LLMs were a thing. While we weren't into academic engineering patterns and buzzwords, we were very particular in maintaining consistent patterns across the codebase. The output of Copilot, even with early models which were far from today's standards, was often scarily accurate. It was far from genius but i'm still chasing that high to this day, to me it really indicated that we had made this codebase readable and actionable even by a new hire.