Yes, PBE is a small server for testing purpose which do not need extra players when it's full. However, this is NOT the way to collect data.
If half of the players always log out after game, other half only play 4 hours per day then AFK. Then only half of the population keep producing data, other half of the resource is wasted 80%.. ( 1 - 4/(24-4) = 0.8, let's say around 4 hrs maintenance per day to make number more friendly). So the total productivity for whole client would be only 60% .. ( 1/2 100% + 1/2 (4/(24-4)) = 0.6 ). Also guess what will happen, more and more players will AFK because it's annoying to wait in queue, the total productivity would drop to 20% eventually.. ( 4 /(24-4) = 0.2 ) .
So please give the spot for active players to keep PBE highly used.
P.S. I think 1 hour afk is reasonable. Please correct me if i did my math wrong... but you guys get my point right?