The best approach is never to get remotely close to the point where it auto-compacts. Type /clear often, and set up docs, macros etc to make it easy to built th

The best approach is never to get remotely close to the point where it auto-compacts. Type /clear often, and set up docs, macros etc to make it easy to built the context you need for new tasks quickly. If you see that 20% remaining warning, something has gone badly wrong and results will probably not get better until you clear the context and start again.