I think there is a misunderstanding. What I am asking for is to bring back the old mechanic where zombies all spawn in the POI at once instead of the current system where rooms fill up as you enter them.
Going by the complaints I've seen on the steam forums, players who nerdpole their way up to rooftops notice a lack of zombie sleepers. However, once they set foot on the roof, they all not only magically appear, but suddenly wake up. From what I understand, this new spawning mechanic is not only a new thing introduced in A21, but is also particularly frustrating for players who specialize in stealth play, as picking them off one by one from a distance while they're still idle is impossible since they don't exist until you reach a certain point in the POI.