Aren't subdirectory specific Claude files layered in on top? Seems like more required content when the direction I'm suggesting is more like lazy-loading.
For example, I have one in my schema migrations directory that explains how to write migrations with appropriate concern for forwards- and backwards-compatibility in our deployment model.
This is effective only if you're guiding it heavily though - this is a very human-supervised workflow, and I'm telling it when it's time to take specific actions. It will read the appropriate instructions file when the action is first referenced, but not until then.