but she actually doesn't follow the same path.
The film shows the lady walk the exact same path to get to #17 that B&R walk down, so IDK why you see it differently.
In order to take the same path, she would have to walk past that wooden door
We're both focusing on different wooden doors (though I do see the importance of the door you're talking about, as it's also shown twice and further proves how nonsensical their walk really is). In my OP, the door shown in the first pic is the one I find important, because it's shown in a close-up
POV shot, twice. Once before they reach #12, and again after they leave #12 as they walk to #17. This door and apartment has a creepy tree in front of it, and the apartment seems to be placed in front of #17, because when B&R are standing in front of #17 (which, again, is a shot that is also shown when they arrive at #12 for some strange reason), we can see the tree behind Betty, to the right. This is further confirmed by that fact that, during that walk to #17, before we see the close-up of this "mystery" door/apartment as B&R walk past it, we see B&R look in the direction of it, and if you look at Rita, she seems to signal Betty to look at it, by nudging her head in its direction, and as the POV shot of it pulls away, it cuts back to B&R as we see Betty turn her head away and back toward #17 straight ahead.
I suppose it's entirely possible that there simply isn't enough space in the courtyard between #12 and #17 to do all the filming that Lynch want's. So he places the girls back to the entrance of the courtyard and starts filming from there as though they are walking away from #12, and then just hopes that nobody notices that they're actually back where they started.
I disagree, I think it is all intentional b/c there are far too many obvious inconsistencies. It's such a juicy segment of the film, filled with many subtle clues. And b/c of the fact that, when they first arrive at #12 we see B&R with the same background as what we see when they reach #17 makes me wonder if they are both the same apartment somehow, for some reason. And if that is so then you are correct that we aren't seeing them leaving #12 to walk to #17.
Go to this scene, and when the film first shows the facade of #12, and then cuts back to B&R supposedly standing in front of #12, look at the background and notice how it's the exact same background as what we see as they walk to, and arrive @ #17. Then when Rita tells Betty "WAIT!" notice how the background suddenly changes completely.