Ya didn't really think they build a long freakin' hallway, did ya?
Well, they are always bragging about how huge the DS9 sets were. The find in the OP, presuming it is an accurate analysis, seems to fly in the face of them taking great pains to build huge sets. If the photo theory is true, then that's evidence of them cutting corners to make the sets appear bigger than they are.
That's not cutting corners; that's building to the physical limitations of the sound stage. There's not infinite space in there, and if you want other more interesting sets you're better off building your hallway short.
You know, come to think of it, I have never seen the actual DS9 set plans. The most I've seen are the Promenade layouts from the DS9 TM. Kind of odd, when you consider how easy it is to find the TOS and TNG/VGR set plans on the internet. (I don't think I've ever seen the ENT set plans, either.)
I think the old "Making of Deep Space Nine" book that came out between season 2 and 3 has a map of the how the sets were arranged on the stage.
Did you remember the main hall in Babylon 5? That was the worst hallway mat painting EVER! lol
The hallway painting for the corridor in Babylon 5 was only used in season 1. They physically extended it in season 2.