As I experience it's more important in Jade than it is in Adom just to fight one monster at time. As oft that my usually procedure for a room in a dungeon with more than one monster in, is to lure them into a corridor an kill them one by one. That's a little boring for three reasons. First of all it's the same procedure for every room. Second it isn't a real fight anymore, it's just killing. And third the difference of the difficulty is to large (as i see it).

So I thought that maybe the monsters could recognize if the are alone or not and in that case there might be a random chance that they won't go into a corridor and group around the door if a PC is near or just stay somewhere in the room.
Maybe that would give some more importance to the stealth skill, too.

'Hope you can understand my stammering ;-)