Vocals outputs individually or mixed together?

[kanuck]

I used the search function but I couldn't find anything about vocals. How bad is it to send to the sound engineer a stereo out mixing everything (drums, guitar, vocals, bass)? Is it absolutely necessary to send an individual output for the vocals? The consensus here seems that it's ok to send all of your stuff as a single stereo out for the electronic musicians here but I couldn't find anything about singing. I would send it individually but the problem is i'd only have a mono out and would prefer having the vocals stereo too so I can play with ping pong delays and such. Thanks.

[Grottoman]

Good question, i asked something similar once, the response was to send the whole stereo mix. Don't listen to me though, I'm interested in what the professionals got to say.