For Outlook: according to Microsoft Support, the calendar will synchronize a couple of times a day. If you want to force the calendar to update, you can remove current subscription and then relink by subscribing to it again. This has worked for some users in the past.
For Google Calendar: Google does not have a definitive statement on how often the system will synchronize the calendar. Some forums suggest it can take up to 24 hours. Removing a Google Calendar subscription and re-adding it will not force an update.
Unfortunately, the updating frequency of third party calendars is out of our control. If your calendar does not update after 24 hours, please get in touch with us and we will help investigate it.