By volume three it still hasn't delved deeper into the intense (and more apparent) class-divisions. There are a few instances of the upper-level persons claiming resources from the lower levels, including the lower-level residents' own homes. There's a bit of anger, and then "oh, they sent me to a new home, same as the one before." so the story is...the rich will destroy our homes, only to ambiguously hand us a new home? How is that even possible on a life system dependent on space, resource, and population control?
Continuing from volume two, there are still a few, less intrusive moments of characters having meals together. Still unnecessary, still annoying. There are a few growing plots from earlier (presented as a cliffhanger), such as going down to the surface. But by now, I'm done trying to skim through the filler to get to the good parts. Therefore, I'm likely done reading through the series.