In an adjudicatory proceeding, all parties shall be afforded an opportunity for hearing within a reasonable time, said time to be, unless otherwise provided by statute or regulation, 120 days from the department's receipt of a complete application for a license or permit or other accrual of a right to an opportunity to be heard, or in a proceeding to consider suspending or revoking an existing license or permit, from the department's issuance of a notice of hearing, provided that the department may extend said period for good cause, including but not limited to the need for further investigation, pending judicial proceedings, the convenience of witnesses, parties, department personnel and hearing officers, or extraordinary circumstances, and further provided that this section shall be directional rather than jurisdictional and shall not affect or impair in any way the validity of any adjudicatory proceeding.