my $target_days;
if ($data{day_name} =~ /fri/i) {
   $target_days = \%p_list_fridays;
   $fridays++;
} else {
   $target_days = \%p_list_weekdays;
   $weekday++;
}

$target_days->{$data{doc}}++;
# instead of
# $target_days->{$data{doc}} = $target_days->{$data{doc}}+1;