You can use the guide for a day with high information density, food or craft topics, complex transfers, or areas where you want to ask questions while walking.
Ask clearly about this day, not just your aptitude
Confirm the rhythm, meeting point, included items, language, accessibility, cancellation clauses, and how to adjust in case of weather or physical changes.
Leave space for dialogue
Guide days only truly work when the itinerary isn't packed to the point where you can't talk, observe, or make last-minute turns.