I stumbled on this panel, that I'd painted about a year ago. I couldn't help but notice that it looked quite washed out, and there weren't any real dark darks. So, I thought I'd just paint over the piece and see if it would be improved by beefing up the contrast.
I don't know that it wound up any "better", but I do like the increased contrast and the better definition of cool shadows. I might try this with a few other close failures from last year. Should be interesting.