Requests for extension of time should be served on all parties and should set forth the reasons for the application. Applications may be granted upon a showing of good cause by the applicant. From the designation of a presiding officer until the issuance of a decision such requests should be addressed to the presiding officer. Answers to such requests are permitted, if made promptly. [35 FR 10760, July 2, 1970, as amended at 51 FR 10386, Mar. 26, 1986]