The Session time listed in the Inventory pages is not the value that the Global Session timeout uses.
The Session time is the total time a session has been active on that particular VM. This essentially means how long a user account has been logged into the Windows OS in the desktop VM.
The Global Session timeout only applies to single client sessions. So if I connect with my iPad and hit a timeout set at 930 minutes then I will disconnect. But if I connect for 600 minutes, disconnect and then immediately reconnect I can stay connected for another 930 minutes.
I can explain further if needed.
-Mike