How often does Google Sync refresh / update / sync with Google Apps Calendar?
When a change is made to the Calendar on the device, the Google Sync will sync with Google Calendar within 10 minutes of the change being made. If there are not changes, automatic synchronization happens about every two hours. The actual sync interval is a random time between 1h45m and 2h15m. This was designed to reduce peaks in traffic to our mobile sync service.