I’m now using the arming schedules, but it doesn’t seem like I can simply have a disarm scheduled… am I missing something?
No, currently you would need to create a schedule for arming as well, although this is a known sore point and the capability has been requested from Alarm.com. Even the description on the arming schedules page suggests that arming and disarming can be mutually exclusive.
There is no ETA on when the functionality will change, but it is being worked on. The schedules were intended for Commercial customers primarily, and are even relegated to the Commercial tab on Alarm.com.
Oddly you can choose to only arm.