There are some people participating in the study who will fire & forget instructions to Claude/Codex running in parallel worktrees, but would really struggle if they were required to work on their project without AI assistance.

So while some study participants probably are seeing an actual speedup because of the discipline with which they manage their codebase's structure & documentation, other study participants are actually getting worse at non-AI coding.

...and METR's study can't tell which is which because METR's study isn't using any sort of codebase quality metrics for grounding.