When temporary disablement or sickness has continued for not less twenty-eight days and the Insurance Medical Officer is satisfied that such disablement of sickness is likely to continue for a long period and that, owing to the nature of the disablement or sickness, examination and treatment at intervals of more than one week will be sufficient, the insured person may, unless otherwise directed by the appropriate office, furnish medical certificates in the form of special intermediate certificate (Form 8) at intervals of such longer periods not exceeding four weeks as may be specified by the Insurance Medical Officer.
