As many reverbs as work for a person I suppose. So long as it's basically just the one in a project lest things sound as if they're in different rooms.
I only use ReaVerb BUT I have a bundle of files & convolutions to load into it. Mainly I use just the one, and lightly, on the full drum kit with touches here & there on solo instruments or a tiny bit on vocals.
The Abbey Road stuff sounds great and is amazingly cheap but I'm not bothered - I'll just get reverb drunk again and once off the wagon it'll be swamp textures to the moon & back.


Cheers
rayc
"What's so funny about peace, love & understanding?" - N.Lowe