I have an MX unit setup to require everyone to login every 12 hours i.e. splash page pop up. What I have noticed is that it seems a little bit broken.
Google.com, Facebook, Apple, AirNZ pages all contiune to work without the splash plage coming up.
Crashplan, local news site, banking website all require me to login.
The Apple and AirNZ pages are not cached in my browsers history as I hardly every visit them, I have even tried another browser....
In short it doesn't seem like the enforcement of the requirement to login is working that well...