What do you mean by 'vocal ambience'?
If you mean 'reverb', then, yes, there are no rigid rules, but more often than not, in interior scenes, there will be reverb in all five channels (or four.)
With dubbed dialogue, it is easier to spread it out of the C channel, but I guess mixers job in that case is to make the dub as close to the original as possible without foolin' around
