Define forms the consistency and voice
There are patterns to the juxtaposition of multiple aspects of design, and none more so than color. The juxtaposition of color deeply affects accessibility as well as visual cadence, so having a set of predefined cadence is essential. What I have found through designing permutations is that it also keeps me from forgetting decisions that I made weeks ago, rethinking at point of use, and then realizing while scanning a broader set that I've set up visual dissonance that I neither needed nor wanted.