If I had played this on the real Zutphen organ, it would be for sure much more difficult to change all different registrations within 'no time'. I think you needed three assistants at least!. In Hauptwerk it's of cause just to touch a piston, and then you 're there.
However, to set up a registration plan for a work like this takes a lot of time if you want find a good balance and demonstrate the variety and the beauty of the instrument on its best.
So, I hope you don't get bored listening to so many variations!