Cron every 8 hours: 0 */8 * * *

Eight divides 24 three times, so the runs are exactly eight hours apart with no remainder. The set is small enough to hold in your head, which makes this a good schedule for anything a human is expected to check: three runs, three results, and a gap that matches how shift work is organised in most operations teams.

Because there are only three runs, each one carries a third of the day. That changes how failure should be handled. Silently retrying at the next schedule means eight hours of nothing, so a job on this cadence should retry internally, and it should report a failure loudly rather than relying on somebody noticing a missing log line.

The default alignment starts at midnight, which is rarely when a shift actually begins. Start at step handles this cleanly: 0 6-23/8 gives 06:00, 14:00 and 22:00, and 0 7-23/8 gives 07:00, 15:00 and 23:00. The spacing stays at eight hours in every case because the walk simply starts from a different hour.

One thing this schedule will not do is stay eight hours apart across a daylight saving change in an observing zone. The wall clock is what is matched, so the day the clock moves has one interval of seven or nine hours. If a downstream system genuinely requires eight hour spacing, run the crontab in UTC.