In tracking down some other stuff, I noticed that the freepbx/asterisk crontab is getting rebuilt and reloaded every minute on the system (FPBX14).
A bit of digging on it looks like that the schedtc.php crontab entry is causing itself to be rebuilt every time it executes (which by default is per minute).
(* * * * * [ -x /var/lib/asterisk/bin/schedtc.php ] && /var/lib/asterisk/bin/schedtc.php)
This ends up calling the updateCron() function in /var/www/html/admin/modules/timeconditions/Timeconditions.class.php which causes the rebuild rather than leaving the file alone if the entry already exists. Basically needless work which causes a bunch of extra logging in the system.