Sleeper volumes get alot of hate but without them, performance would be horrible and there would be no pacing whats so ever in dungeon POIs.
Back in the day, there was only one big volume and all of the zeds would spawn in. Not only does this strain the max alive zombie count but also made clearing POIs pretty one dimensional.
One reason ood movies and TV shows are entertaining is because they have good pacing and build up to a climax.
A well designed quest POI will lead the player the right direction without having to relay on the red dots on the compass.
Additionally, there is the orange dot for volumes that were missed by the player.