I don't think LLMs have high information density at all, a huge percentage of what they say reads like filler. They're essentially incapable of being concise.

Which I think is partially evidenced by the "tens of thousands of lines" -- I'm working on a media streaming web app for fun on my own time and the whole project is yet to crack 10,000 lines (excluding libraries) including both the backend and the UI. When Claude shows me huge diff at work my first thought is "no way, there's got to be a cleaner simpler way to do this" and there always is