Unless the order of presentation at a hearing is otherwise directed by the presiding officer, the agency, party, or person who initiated the proceedings or its duly authorized representative shall briefly state the nature of the matter to be heard and proceed with the introduction of evidence. Other interested persons or parties shall proceed in like manner in such order as the presiding officer may direct. At the conclusion of all the evidence, the presiding officer may, at his or her discretion, allow oral arguments.