Any party who desires a continuance shall, immediately upon receipt of notice of a hearing, or as soon thereafter as facts requiring such continuance come to his knowledge, notify the board of said desire, stating in detail the reasons why such continuance is necessary. The board in passing upon a request for continuance, shall consider whether such request was promptly and timely made. For good cause shown, the board may grant such a continuance and may at any time order a continuance upon its own motion. During a hearing, if it appears in the public interest or in the interest of justice that further testimony or argument should be received the board may in its discretion continue the hearing and fix the date for introduction of additional evidence or presentation of argument. Such oral notice shall constitute final notice of such continued hearing.