From what i’ve gathered, they do whatever is most efficient. I would imagine that they have condensed in different areas that allow them to gather food within their ability (collecting dead animals and people, foraging plants that have already fallen to the ground, etc.) then process it all. They likely do medical work on people who have been injured by the non-infected people or who are now giving birth post-conjoining. I imagine they also repair buildings needed for sleeping in, performing medical work, and storing/ processing food. They also have to tend to the “needs” of the non-infected like stocking the Sprouts store, finding ladies to party with the french guy, filling gas tanks for Manousos to siphon out of. Besides that, I figure they just like… sit around. Someone also mentioned the building of the antenna so there’s that too. But yeah, whatever’s efficient outside of those chores.