I've done turnarounds with colour-schemes for some of them, yeah! Weirdly enough, not for all of the main characters, but that's the process for you. ^_^; I should probably do proper turnarounds of all of them one of these days, though. It'll definitely help with keeping their heights consistent and all the details correct - I keep drawing Chouko's sword on the wrong side in my sketches.
When I do them properly, they look a bit like this:
These are minor characters - a couple of thugs from chapter 5 of Grassblades - but I needed their uniforms to match, and their colour-schemes needed to work for a bunch of other characters as well, since they're, well, a uniform.
I don't do this for ALL characters (as mentioned, some of the main characters are still missing turnarounds), but it's a useful tool, especially if the characters leave the story for a while and then come back later, and I've forgotten the details of their costumes.