I face the exact same dilemma in my field of interest - time management. The fact is, most authors and content creators focus their advice at the beginner-level for several reasons...it's easy to explain, applies to a mass audience, and sells better. But they themselves don't read beginner-level stuff. They hire coaches, and eventually learn how to diagnose their own performance at an expert level. Think of Lewis Hamilton, Tom Brady or Serena Williams.