Thinking of this thread, I came across this image.
http://www.theguardian.com/artanddesign/gallery/2014/dec/24/best-portraits-of-2014-in-pictures#img-3
I think this is an example of the deepness of shadow and black that you reference.
Firstly, let me say, I have no experience with this type of subject.
However, looking at this young man's face on the left side, our right side, there is basically textureless dark. Even the lit side of the face is (on his extreme right face) tectured black.
This young man's face really is only modelled by the reflection of specular light, which is difficult to read with a meter.
His shirt is not over (or extra) exposed, so I expect this was shot equivalently to a incident meter or perhaps reflectively off of a grey card sort of metering.
The whole idea of metering is so interpretive, I expect that I would need to see prints of the different options, but I don't see that giving this scene more exposure (based on the blackness of the face) would improve it.
(And yes I know the whole image is not real to us. Please pretend.)