We'll create fresh WordPress site with Snack Missed Schedule installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Unlike other plugins, where check for missed schedules is hooked into init action, which in return means, there’s an extra database call created anytime the site is loaded, this plugin creates separate recurring cron task to check for missed schedules.
Checks are happening every 5 minutes and in case there are found posts missing its schedule, they are automatically published. From the principle this solution requires a functional WordPress cron subsystem.