//They need to produce the same output in a shorter period so they are either more efficient or are working at a faster pace.//
Indeed. So the managers of these firms now need to announce that the experiment has been a roaring success. They should congratulate their staff, emphasising that they have obviously cracked on and demonstrated that they can get five days' work done in four. What will follow, they should say, is an increase in workload to fill the fifth day as they were obviously slacking prior to the experiment.