So if I left a device on with Netflix in another flat, have a 2 user account, and my wife is watching something now - I'm getting the message that I can't watch because too many users on the account are watching.

Is there a quick and easy way to boot everyone (my wife would be able to easily re-connect) and watch? 

The "Sign Out of All Devices" page here https://www.netflix.com/ManageDevices says "This may take up to 8 hours to take effect on all devices and affects all profiles in this account."

Is 8 hours the best I can do?