This is not always a bad thing. Consider the following:

  my $current_month = Month->new();
  my $end_month     = Month->new()->plus_months(4);
  while ($current_month <= $end_month) {
    $yyyymm = $current_month->strftme("%Y%m");
    $last_day = $current_month->last_date()->strftime("%Y%m%d");
    $first_day = $current_month->first_date()->strftime("%Y%m%d");
    
    $dbh->do("create table my_partitioned_table_$yyyymm
              () inherits from my_partitioned_table");
    $dbh->do("alter table my_partitioned_table_$yyyymm
              add constraint ck_my_partitioned_table_$yyyymm
              check (date between '$first_day'::Date and '$last_day'::Date)");

    $current_month->next_month();
  }

This makes sure that my_partitioned_table has month-based partitions 4 months into the future (so long as you keep it on cron).