When I was doing a really large refactor across the codebase I told Claude Code to explain how certain things worked currently and how I wanted things to look like after the migration and a plan on how to get there. Then I did several further clean sessions where I always started along the lines: "Using this plan {link} do X."

Works pretty well for "non-permanent" instructions (you don't want to put this info into your committed markdowns).

My main motivation was simply to save tokens, but it actually worked really well and improved speed as well.