Disabling automatic refresh for snap from store

[niemeyer]

I’ve posted the proposed syntax for within-the-month refresh windows as an answer to this existing topic:

Refresh scheduling on specific days of the month

The directions in the refresh schedule documentation only specify a daily time window. How can the refresh be set to a particular day of the month or day of the week between specific times? What is the command to reset the refresh schedule to the default SNAPS refresh schedule behavior? Is this feature persistent through Ubuntu server system reboots?