I mean, they did the black wall finale like Orlando (which means they get a pass), they had black walls in the Upside Down (again, a pass because it's dark), and I think there was one or maybe two short hallways. Nothing as egregious as "Poltergeist", "Halloween 4", or "Trick r' Treat". All of those were NOTICEABLY barren while "Stranger Things" felt much more built out.
But back to "Us", do we think the mirror maze will be at the beginning and near the end? They mention it being near the beginning in the article.