I'm sorry Bethesda BUT WTF ARE YOU SMOKING.
If the system let you see their preferred room type AFTER you have upgraded all their skills then maybe this is doable... But when you have everyone in your vault upgraded past their original stats it ends up being a VERY frustrating job of "Drop him in here... nope... nothing... Drop him in here... NOPE... GRRRR... Drop him in here... ARRGGHH... NOW I HAVE DROPPED HIM SOMEWHERE AND I CAN'T FIND HIM..."
If you are going to make useless chores at least give us the information to let us complete it. As it is, with the poor interface controls, lack of character preference information and losing having to move characters from rooms where they are already working at max efficiency then all it is is a pain in the asteroids.
Now I hear you say "If they are trained up in your current room then that is their "correct" room. Well apparently not. Something isn't working right because if a character is trained up to 10 P and their initial high skill was charisma then the "correct" room is the bar or the radio room. But as you have trained them up in water processing it should be their "correct" room... Now if you could see a character's original stats then this objective of assigning to the correct room is doable (but still a pain).
Currently you cannot tell what room they should be in... and that svcks!