Scheduling firewall or QoS changes based on time interval?

I know that you can schedule basic firewall changes via the Web UI with start/stop times for specific days of the week.

However - how would you schedule more advanced time changes - for example, on an interval? (e.g. once every 6 hours, or once an hour etc.)

For example, if you only wanted the rule to apply for 5 minutes every 6 hours etc.)

And can you also do this for QoS (e.g. Advanced Queue) changes as well?

(I was thinking you could somehow put the CLI commands into a Cron file somewhere - but I'm not sure how to do this within EdgeRouter).