Outlook Refresh Interval for iCal subscriptions (webcal://)

With many calendars being integrated into the Cloud, these settings (X-PUBLISHED-TTL and REFRESH-INTERVAL) no longer work on Google Calendar and many newer versions of Outlook. I've tested this myself.

If you think about it, Google and Outlook likely and intentionally ignore any specified refresh rate to prevent DNS attacks. Basically, with millions of integrated calendars in their systems, some people could set a refresh rate every second and if they obey these settings, it could crash their servers. So, it's likely that they refresh whenever they feel like it.

For Outlook 2013 if you hit send/receive that will sync the calendars as well. To adjust that interval go to File > Options > Advanced then scroll down to find Send/Receive. The options to adjust the intervals for auto Send/Receive are found there.

Outlook relies on the custom property X-PUBLISHED-TTL to set the download frequency but unless set in the file you subscribe to, there is no way to force within outlook an update frequency (nor in google calendar).