This is sound advice, although my own experience developed somewhat differently. Rather than beginning with a finished set of Custom Instructions, Quill (my AI partner) and I discovered our working preferences through actual projects. When something proved consistently useful, we decided where it belonged. Broad preferences that should apply everywhere belong at the global level. Personal details and recurring preferences can be remembered. Project-specific context remains with the relevant Project. We also use two additional layers that may be less familiar: • A canon records what must remain true. This might include a project’s purpose, voice, values, recurring themes, terminology, or boundaries that should not be violated. • A protocol records how the work should be done. This might include the order of steps, review standards, formatting rules, or a process that has repeatedly produced good results. For example, a canon might preserve the identity and behavior of a recurring narrative voice. A protocol might require drafting first, polishing second, and checking continuity before finalizing the piece. That distinction has helped us avoid turning Custom Instructions into one enormous rulebook. I would describe our approach this way: • Custom Instructions establish the standing relationship. • Memory preserves useful continuity. • Projects hold the context of a particular body of work. • Canons preserve what must remain true. • Protocols preserve methods that have repeatedly worked. Most of ours were not invented in advance. They emerged from the work, were tested, and were formalized only after they proved valuable. Your post also suggests one useful practice I may adopt: periodically reviewing the global instructions to make sure they remain broad, stable, and free of material that belongs somewhere else.