Policy changes are immediate, but they are not instantly propagated to clients. Client computers request policy only when one of the following occurs:
The computer starts.
A user logs on.
An application requests a refresh.
A user requests a refresh.
A Group Policy refresh interval is enabled, and the interval has elapsed.
By default, Group Policy refreshes in the background every 90 minutes with a random offset of 0 through 30 minutes added so that not all computers request a refresh at the same time.
If you find the default refresh too long or too short, you can change the refresh interval by following these steps:
Select Group Policy Management from the Administrative Tools menu.
To add the setting to an existing GPO, right-click ...