I have a hard time understanding this aswell, seems like a waste of good plates to me
I guess that by increasing the distance between the plates that are actually in use, the resistance in the water increases since the electrons would have to travel further or something like that. If that is the case, then why is a plate needed at all? To slow down the flow of electrons even more?
I'm going to go with a +-+-... design until someone can explain why using neutral plates would increase production. If it gets too hot I suppose the best solution might be to cool it in some clever way.