Before closing a hearing, the administrative law judge shall inquire of each party whether he has any further evidence to offer, which inquiry and the response thereto shall be shown in the record. The administrative law judge may hear arguments of counsel and may limit the time of such arguments at his discretion, and may, in his discretion, allow briefs to be filed on behalf of either party but shall closely limit the time within which the briefs for both parties shall be filed, so as to avoid unreasonable delay. The administrative law judge shall also ascertain whether the parties desire to submit proposed findings and conclusions, together with supporting reasons, and if so a period of not more than 15 days (unless extended by the administrative law judge)—after the close of the hearing or receipt of a copy of the record, if one is requested—will be allowed for such purpose.