if you want the mix to sound like it was recorded in an actual room, as if you were in a nice pro studio with a large room that had it's own sonic fingerprint...
then only use one reverb.
set up a separate buss for just reverb, and send varying amounts from individual tracks, to it.
i use a single reverb usually, along with a (2) delay busses, one short, one long.
unless you are going for a special effect, in which anything goes.