Huh, now I feel I've made you think like they are useless. I will need to elaborate!
I think they are a great tool to speed things up when used in moderation. Normally to do a red or white like that I would go through the following process: basecoat (2 layers), apply wash, re-apply basecoat, and then two to three highlights. That's my go-to method for tabletop dudes. With contrasts it's: contrast, then 2-3 highlights. Suddenly I can cut out the three initial steps, which is a real game-changer, when it comes to speed. Contrasts are also really good when attempting to achieve vivid colours. Grey-seer works like a charm here, as it really makes the colours pop. Contrast paints look very bright and charming when highlighted. Try looking up the 'Eavy Contrast series by Juan Hidalgo on youtube, he really nails this down. I am no near his level of skill of course, but the general principles he shows are solid in my opinion.
@Jmash - I suggest you keep trying them out a bit more. I wasn't sold on them at the beginning also, they take a bit of practice to get used to. If you feel they are coming on a bit too strong and the recess shading effect isn't very pronounced, perhaps try thinning them down a bit with contrast medium. It can help. Another thing is not to think about them as a 'magical painting sauce' that one just slaps on and they do all the work. That's how I've used them at the beginning and was also disappointed. But then I started to work the paint with a bit more control, push it around, use it to shade and then I've had much better results. I hope you can make some use of them.
