Office 365 Calendar Updates - not using a shared calendar

The admin for one of our C-level directors creates a meeting invite and sends to multiple staff.  She has access to read the other staff calendars but not edit directly.

When she modifies the meeting (date, time or duration) she will see the update in the C-level calendar immediately, but the update does not sync with the other calendars for some time.  Being the all-knowing control freak.... she is expecting that all of the calendars will sync the moment she changes the calendar entry.

I feel this is probably due to each client syncing on a regular/timed basis but not finding anything to support that.

Thoughts...

Thanks

MD