If you're being paid regardless then what does it matter if you're "on the bench" for a few hours or you leave early for the day? A lot, if we're talking about employee morale. Not much if someone is sitting at their desk trying to find stuff to do.
So long as there is effective communication (which I know can be a challenge) then it really doesn't (or shouldn't) matter when a person is working if the gets done. No?
40h (or 32h) work weeks make even less sense when you work remotely.