We'll create fresh WordPress site with WP Cron per Action installed. You have 20 minutes to test the plugin after that site we'll be deleted.
If there is an action scheduled for WP Cron with a heavy routine which consumes time, the rest loaded due actions will have less remained time and more chances to reach the PHP’s maximum execution time.
If you constantly keep getting the PHP error running out of execution time with scheduled actions, try this plugin and see if the problem goes away.