I hear people saying they are having a hard time finding the npc they need to use seek survivors. Is this a real possibility, or do you not need any you don't start with to use seek survivors. I have never felt the need to cast it so I don't know.
I can't remember what the NPC is that is required to cast that; but it's certainly possible to not have that sort of NPC, whichever the type is. The game is incredibly forgiving in what kinds of NPCs it gives you as you get NPCs, though, so if you get 6 NPCs then you'll wind up with one of each kind before you start getting any duplicates.
OK, then it would seem a good idea to give the seek npc guy first every time, That way if people only every have to go looking for a rescue quest once. After that they can play them as they find them(which as they seem to always be close to stash/gem rooms seems to be how they were indented to be used), or just cast seek survivor if they need some one right now.