(a) Opportunity to file. Before an initial decision is issued, each party shall have an opportunity, reasonable in light of all the circumstances, to file in writing proposed findings and conclusions together with, or as a part of, its brief.

(b) Procedure. Proposed findings of fact must be supported by citations to specific portions of the record. If successive filings are directed, the proposed findings and conclusions of the party assigned to file first shall be set forth in serially numbered paragraphs, and any counter statement of proposed findings and conclusions must, in addition to any other matter, indicate those paragraphs of the proposals already filed as to which there is no dispute. A reply brief may be filed by the party assigned to file first, or, where simultaneous filings are directed, reply briefs may be filed by each party, within the period prescribed therefor by the hearing officer. No further briefs may be filed except with leave of the hearing officer.

(c) Time for filing. In any proceeding in which an initial decision is to be issued:

(1) At the end of each hearing, the hearing officer shall, by order, after consultation with the parties, prescribe the period within which proposed findings and conclusions and supporting briefs are to be filed. The party or parties directed to file first shall make its or their initial filing within 30 days of the end of the hearing unless the hearing officer, for good cause shown, permits a different period and sets forth in the order the reasons why the different period is necessary.

(2) The total period within which all such proposed findings and conclusions and supporting briefs and any counter statements of proposed findings and conclusions and reply briefs are to be filed shall be no longer than 90 days after the close of the hearing unless the hearing officer, for good cause shown, permits a different period and sets forth in an order the reasons why the different period is necessary.