In any proceeding in which the Commission is authorized to act after opportunity for hearing, if the parties waive hearing, such opportunity will be deemed to have been afforded by service or publication in the Federal Register of notice of the application or other initial pleading, request, or other filing, such notice fixing a reasonable period of time within which any person desiring to be heard may file a protest or petition. Upon the expiration of such period of time, in the absence of a request for hearing, the Commission may forthwith dispose of the matter upon the basis of the pleadings and other submittals and the studies and recommendations of the staff. A party not requesting oral hearing in its pleadings will be deemed to have waived a hearing for the purpose of such disposition, but will not be bound by such a waiver for the purposes of any request for rehearing with respect to an order so entered.