Plate camera: Double extension

Is double extension have any other uses than close focus and macro work?

Why because, I am seeing some nice Patent Etui camera in auction, in which some are not having the ground glass but with double extension and the other which have ground glass do not have the double extension.

Can't decide which one to get....

Most "plate" or folding metal cameras has possibilityto change lens in different ways.
By changing lens elements or lens with shooter itself.
So double extension means that you can use longer lens.
This teminology comes from large format photography (4x5 5x7 8x10 or bigger) where double extension bellows mostly is standard equipment.

why do you want to buy one at all? can you still buy cut film in appropriate sizes or are you planning to coat your own plates?