I did a mystery quilt two years ago that my poor fabric choices meant the feature blocks didn't show the piecing well at all. I had too little contrast between my background (black) and print (black and multi-coloured). The print had too much black space and thus you didn't see the piecing/final design (think Maple Leaf block).
I intend to rip out all those blocks and replace with a single block of the print.
Lesson learned - I don't like mystery quilts where you don't know how the fabrics will come together. I've felt like this for awhile, but this one was the reinforcement of why I don't like mystery quilts.
It sat forlornly on the shelf because I didn't want to finish it like it was and didn't know how to correct it. I even tried decorative stitching around the design of the block to try and emphasize it to no avail....now it has a date with Jack the Ripper....