Glazing isnt a new thing
It lets you make use of underpainting, and lets you achieve lots of colours that werent previously possible with the paints at hand.
Its a pretty staple technique used in all sorts of art applications.
Airbrushers call their glazes candies, allthough candies are technically dyes suspended in lacquer (which means theyre actually transparent and will always show the under painting no mater how many layers you go with).
The next step is to learn to mix colours by layering glazes; many airbrush artists have no need to mix colours prior to spraying as they mix them in transparent layers.
I've not tried it with
GW's latest glaze paints, but I'd be interested to see if they become opaque after so many layers or if they indeed always show the under painting (most transparents do this.. only really candy paints do not).
Edit; as far as i can tell the main difference between
GW's 'shade' and 'glaze' is that a shade is a dark colour and a glaze is not. The glaze still pools up in recesses if you let it. but as the colour is bright and not dark it will just lead to a weird effect of the colour being more saturated in the recesses if you allow pooling.