Hi David, this is on our roadmap-- calendar views for things like this.

Turns out that a default Win7 install (chosen to keep parity with our dev environment) has power saving enabled. Disabling sleep seems to have solved the problem. I am not a smart man...

The ScheduleExecuterThrottle value on the Advanced/Internal Settings page found under Admin determines how often this polling occurs (it also controls the polling for whether it's time to do a scheduled build). The field specifies polling frequency in minutes.