Gloria, I have heard that somewhere before, but whether it's true or not or why it's true if it is, bigger, livelier rooms?? who knows?
What I have discovered, using this m/s tool,
http://www.brainworx-music.de/en/plugins/bx_control_v2 , is that when I listened to Aaron Neville songs off one of his cd's, (and discovered by soloing, in m/s mode, the left channel and the right channel) is that a clear vocal is located in the left side channel, and in the right side channel is a lot of reverb.
So as a practical experiment, I made a vocal track, I also copied it to a new track. The original track I pan left with the Brainworx tool, m/s mode. The copy track through the inserted brainworx tool, pan right, also inserted is reverb preset, on 100% or a little less, suite to taste. Yes, the copy track is swimming in reverb, and unintelligible and sounds ridiculous by itself. You can play around with the track panning and volume of each of the two tracks. The copy (reverb) track will have less volume, but the result is amazing!
It's like when you hear a lot of the old recordings and the vocal is clear, however you know they used a lot of reverb, because you can hear the reverb garbage after a vocal pause.
It's unlike the usual recommendation of having 1 vocal track, and using the reverb as a send and return, or even as an insert and adjusting the percentage of the effect. It's possible the send and return was used in the old days, and sounded like the 'new' method because of the delay, the time it took for the signal to go to the basement, or wherever the plate was stored, and back to the room where the return was that did the recording of the signal. Maybe that's why the "in the box" effects don't seem to have the same effect on the signal??
Gloria, I think the real question isn't whether to use reverb or not, but really about what you want to sound like, the best way is probably finding a cd that sounds like you want to sound, and mixing to that, a reference cd.
Hope that helps,
~Len