<?php
 
$feat = ['featured', 'featured', 'featured'];
$no_feat = ['brrh', 'brrh', 'brrh', 'brrh','brrh', 'brrh', 'brrh', 'brrh', 'brrh', 'brrh', 'brrh', 'brrh'];
$all = [];
$h = 0;
$all_len = count($feat) + count($no_feat);
for($i = 0; $i < $all_len; $i++) {
	if($i%5 == 0 && count($feat) > 0) {
		$all[] = array_shift($feat);
		$h++;
		continue;
	}
	if(count($no_feat) > 0) {
		$all['no_feat' .$h][] = array_shift($no_feat);
	}
	else {
		$all[] = array_shift($feat);
	}
}
print_r($all);

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