For at least some codebases, I'm not sure this is a useful metric. Because you don't usually put the whole codebase in your context at the same time.

For example in my current case, there are lots of files with CSS, SVG icons in separate files, old database migration scripts, etc. Those don't go in the LLM context 99% of the time.

Maybe a more useful metric would be "what percentage of files that have been edited in the last {n} days fit in the context"?