Can clean_log_tables be used for weekly bucket system

Clean_log_tables is used to clean log tables like audit_trail and audit_values. The code seems to be only used for monthly bucket system. The example code is as follows:

vd_start_time := DBMS_UTILITY.get_time;

   get_param('sys_params','audit_history_length',vi_months_to_keep);

   vs_msg := 'is_method => '|| NVL( is_method ,'NULL') ||', audit_history_length => '|| NVL(TO_CHAR( vi_months_to_keep ),'NULL');
   DBEX(vs_msg, vs_proc, 'C');

   IF vi_months_to_keep > 0 THEN

      vi_months_to_keep := -1 * TO_NUMBER (TRIM( vi_months_to_keep ));
      vd_end_date       := add_months (CAST(SYSTIMESTAMP AS DATE), vi_months_to_keep);