Partially updates the staff member's working hours: timezone, weekly availability and date overrides are each updated only when present in the request, and keep their current value when omitted. Note the difference between omitting availability or overrides and sending an empty array - an empty array clears the existing entries, which for availability leaves the staff member bookable at no time at all. When availability is present it replaces the whole weekly schedule rather than being merged into the existing slots, so send the complete set of slots you want.