In your case, the head server may only provide the usual, relatively transparent management function in the dining room. You may only see the head server if something is not going according to plan, and that’s a goo thing. The standard $1/person/day is quite appropriate in this situation.
However, other situations may warrant extra attention and what you describe as personal assistance. For example, this comes into play for diners with noted allergies. My wife must eat gluten free. The head server is the point person for managing the process of ordering allergy-safe meals. Even when the server and assistant server are reasonably knowledgeable about GF or other allergy limitations, the head server signs off on the orders. When placing an allergy order at one of the quick serve locations on the pool deck, one of the head servers will be on duty (they all work together in this regard) and will make sure your special order is handled properly. So, for those of us with special dietary needs, the head servers have been a valuable member of the dining team, and we have tipped extra in recognition of this.