In the event that the City fails to answer a grievance within the time required at any step of the grievance procedure, or if the Union fails to appeal the answer given to the next step of the grievance procedure within the time allowed, then the grievance shall be considered settled against the side which has defaulted. However, any of the time limits in the grievance procedure may be extended by mutual agreement; such agreement shall be in writing and initiated by the requesting party. Grievances settled by default cannot be the basis of establishing precedent for the settlement of any other grievances.