This is what was suggested to me by their support however it does not entirely work (on V4.0.3). This is because you must specify "Shutdown idle users after X minutes". For some reason, the schedule does not function with shutting down idle computers with no users logged on very well.
With a 'Shutdown idle users after 5 minutes' management policy set, and the schedule set to 'Set All', it will shut down an idle computer after 5 minutes, but if there is a user logged on and conducting their work for < 5 minutes and they 'log off', the machine will immediately shut down.
With the same management policy set, if the schedule is set to a certain time (for us, it was 4:30, Mon-Fri), it would not shut down idle computers at all. It's as if the policy cannot cooperate with the configuration of a shutting down an 'idle user' on what is actually an 'idle computer' and therefore the schedule does not apply accordingly.
Apologies if my post appears convoluted, I struggled to word this as it's a peculiar issue. It makes sense in the brainbox!