Your solution is fine. Heres how I'd probably write it:

$ cat 11105885.pl
use warnings;
use strict;
use Data::Dumper;

my $bucket_count = 4;

my @array = qw(1 2 3 4 5 6 7 8 9 10 11 12);
my $buckets = [];

for ( my $counter = 0; $counter < @array; $counter++ ) {
  my $element = $array[ $counter ];
  my $bucket  = $buckets->[ $counter % $bucket_count ] ||= [];
  push @$bucket, $element;
}

print Data::Dumper->Dump([$buckets], [qw(buckets)]);
[download]

The result:

$ perl 11105885.pl
$buckets = [
             [
               '1',
               '5',
               '9'
             ],
             [
               '2',
               '6',
               '10'
             ],
             [
               '3',
               '7',
               '11'
             ],
             [
               '4',
               '8',
               '12'
             ]
           ];
[download]