Once your calendar application subscribes to a feed provided by Calendar Sync for Jira, it will continue to receive updates and stay in sync with data from your Jira issues.
When you change feed configuration in Calendar Sync, the same subscriptions will still work. This applies to event contents, but also all the other settings including the fields used for event date/time calculation. The only exception is when you change what fields are used for grouping, since every group has its own, unique link.
The feeds provided by Calendar Sync are updated at most 5 minutes after a change is made in Jira. However, each calendar application has different behavior for the subscriptions, and may take significantly longer to reflect the changes on the calendar. See below for more information on the most popular calendars.
According to its documentation, Google Calendar will automatically refresh the calendar several times a day. It may take up to 12 hours until a change in Jira is reflected in Google Calendar. This delay is entirely under control of Google calendar; Calendar Sync for Jira provides updated data within 5 minutes. Users cannot perform the refresh manually.
Apple iPhone or iPad
Update frequency is configurable in fetch settings. Users can also perform the update manually.
Microsoft Outlook (Desktop)
Outlook synchronizes the calendars whenever the Send / Receive action is performed, whether it's invoked manually or with the automatic polling interval.
According to Outlook.com documentation, it may take more than 24 hours until a change in Jira is reflected in Outlook.com. This delay is entirely under control of Outlook; Calendar Sync for Jira provides updated data within 5 minutes. Users cannot perform the refresh manually.