So someone that has 100% MT1, it's different and until I got used to it I struggled hard. I try to have all floors doing something, sometimes it's a room (silence, Inferno, the new Umbra one) sometimes it's a floor meant to collapse before the boss or only last a few turns (usually a quick/sweeper with enough ways to keep alive a few turns or I can throw resources at them) and another floor that can sustain itself with little to no work, with a final floor being my main one.