> Overall, our results suggest that context files don’t improve coding agent performance, and should only contain specific additional instructions beyond what is already available in the codebase

That's what the study says.

I recently did a much smaller scale test. Some coworker was pestering me about some brilliant skill file so i backed up Claude's state and told it to make a plan for some refactoring task with and without those skills installed.

The results were identical. I didn't measure token use though.