Not sure how others feel, but some of the monolith layouts, feel really sparse on mobs. Some of the layouts it feels like you are constantly in combat, with medium-large packs consistently, which feels really good. Then some monoliths you go in and every mob is by itself or in pairs, and it just feels a bit awkward. Maybe its me coming from PoE primarily, where density is massive all the time, but it feels like in those echos where you have 1-2 mobs at a time, adding some small fluff mobs just to make it feel a bit fuller, would make the echo/monolith experience a bit more satisfying.