24 60 60
Permutations: 86400     Chunk size:     21600   Chunks: 4
$VAR1 = [
          [
            [
              0,
              '0'
            ],
            [
              21599,
              '5 59 59'
            ]
          ],
          [
            [
              21600,
              '6 0 0'
            ],
            [
              43199,
              '11 59 59'
            ]
          ],
          [
            [
              43200,
              '12 0 0'
            ],
            [
              64799,
              '17 59 59'
            ]
          ],
          [
            [
              64800,
              '18 0 0'
            ],
            [
              86399,
              '23 59 59'
            ]
          ]
        ];