scheduled_runs.php

<?php

$now = new DateTime();

$run_01_start = (new DateTime())->setTime(0, 0);
$run_01_end = (new DateTime())->setTime(1, 0);
$run_02_start = (new DateTime())->setTime(12, 0);
$run_02_end = (new DateTime())->setTime(13, 0);
$run_03_start = (new DateTime())->setTime(18, 0);
$run_03_end = (new DateTime())->setTime(19, 0);

if (
    ($now >= $run_01_start && $now <= $run_01_end)
    || ($now >= $run_02_start && $now <= $run_02_end)
    || ($now >= $run_03_start && $now <= $run_03_end)
) {
    echo 'Running :)';
}