Well that is your experience, it's interesting what others have to say too. I have found over 70 CMYK variations of targets that give more neutral patches then others. Still need to think how to analyse them. But patters are emerging.
Not all targets are created equally! In an ideal world, we'd measure all
device values in a defined and large color gamut (so something close to 16.7 million device values). It would take forever and the profile size would be larger than many images. So extrapolation has to take place. Consider post optimization too! Assuming the product(s) you use support this.
Not sure what you need to analyze or how. Perhaps we'll find out what makes a patch '
happy' or '
magical' from your '
analysis'.