I was happy that I pretty much guessed this final answer. And I was only able to do that because of watching and reading the experts here. Those Johnson's are really cool pieces. It would be better to see a whole set in use - at one time. If you want to let me borrow a set I will do that, take pictures and send the set back 8-) Seriously, I'd like to drive a set.
Were they ever actually used that way? I would guess more typically one or two pieces at any given time, but it would be fun to do a combo cook where the full set was working at once.
What does a full set run - I realize it's all about market, etc. etc, but whats the range that a full set goes for. Don't see them that often and when you do you only see parts not sets. Takes the "double skillet" to a whole new level :D Literally.