Approval of a special permit hereunder shall not substitute for compliance with the Subdivision Control Law, nor oblige the Planning Board to approve any related definitive plan for subdivision, nor reduce any time period for Board consideration under that law. However, in order to facilitate processing, the Planning Board may, insofar as practical under existing law, adopt regulations establishing procedures for submission of a combined plan and application which shall satisfy this Article 11 and the Board's regulations under the Subdivision Control Law.