I spent time yesterday pulling out from my non-scrap fabrics, so I'd have enough to go larger.
I ended up leaving out a lot that was too "in between" so that my dark, mid and light were distinct.
sort of like take everything and lay it out in order light to dark, then removed 2-3 "in between" fabrics so that when you jump from one group to the next, there is no doubt that the dark would look wrong with the darker of the mid group, and vise versa.
So my darks are all more burgundy, my mids are all more bright reds, and my lights are coral/dusty rose/pink shades. I've done enough quilts using color groups instead of constants, and I know that it's easy to get the pattern muddled if you don't have enough distinction between groups. For most of the BH mysteries, she gets around this by using different colors, so you won't mix up a red with a blue, no matter how dark or light you go.
This is an example of a quilt that used red, pink and white. And even with this, there are a few places where the fabric didn't read quite correct for the pattern. I even ripped out several of one fabric as when it was sewn in, it ended up too "in between" and muddled the pattern.
BTW - this quilt was designed by Rhonda