The wizard figure I painted was the first to "benefit". I found it to be not particularly fast to use & not obviously better than using the old reliable base/wash & highlight.

However, now that I have a gap in my painting schedule, I've moved back to my DR force - specifically, 4 large trolls.
And here is where contrast paint comes into its own - acres of high relief of scaly flesh. I'm using 'snakebite leather' contrast & it's easy to apply & looks great. And nothing else is needed - no highlighting. The trolls wear lots of armour, which I will painted with Vallejo 'steel' & wash with Nuln oil. Not much else to paint after that.
So, my conclusion - thus far - is contrast works best on bigger figures ( eg > /172) & on highly textured surfaces. Is it of any great use to us smaller scale painters? Probably, not. However, when I've completed the trolls, I'll move on to a unit of 12 half-orc pikemen (1/72) & I'll try contrast paint again. I don't have high hopes but I'll get back to you.
donald