At some point when the number of boxes and number of cronjobs become too high, I suggest looking at Rundeck as a central scheduler (not affiliated with PagerDut

At some point when the number of boxes and number of cronjobs become too high, I suggest looking at Rundeck as a central scheduler (not affiliated with PagerDuty, I actually work for a competiting company) or something similar. Also, you want to make sure your job has been running. I've used a selfhosted instance of healthchecks.io in order to warn me if something has not run.