Meh, I dont think it has to be that complicated. I think that Ways to Faery are specifically more repeatable and stable than the average, since Fairy is more strongly anchored to the natural world directly, rather that linked by mortal subjectivity as completely as with more idealogical domains. This is why it was critical for the WC to secure passage from one of the courts, because those are the only ways that are objective enough to count on for the entire organization. Note that all the way locations we've seen are all relatively static locations: bleak, uniform and inhospitable rental space, stairwell near a abandoned meatpacking plant, etc. These are places with rather old and/or established tones, and so it would take more drastic changes to shit them. If by contrast we were talking about a Movie Screen (and one that wasnt devoted specifically to horror flicks) it would likely open to a wide range of locations depending on which movie was last played and what emotional imprint the last audience left behind.
It was also stated in GS that powerful NN entities can more directly influence Ways, which is why Evil-bob was able to funnel all NN traffic around CT's lair to his Normandy Beachhead. Presumably Lea put similar boundaries near harry to funnel access through her Garden.
Dont get me wrong, Im just talking about Way mechanics; I do also subscribe to the theory that the SG dream scene was a glimpse of the multiverse.
