Based on an examination of the documentation described in § 955.5, the pleadings, and a determination of whether the arguments and authorities addressed to the issues are adequately set forth therein, the Board may, in its discretion, require the parties to submit prehearing briefs in any case in which a hearing has been ordered pursuant to § 955.9. In the absence of a Board requirement therefor, either party may, in its discretion and upon appropriate and sufficient notice to the other party, furnish a prehearing brief to the Board. In any case where a prehearing brief is submitted, it shall be filed with the Board at least 15 days prior to the date set for hearing.