There should be an option in the menu to tell it what you'd like to prioritise, e.g. attack, defence (Goofy and Donald's cards), cure, magic, buffs/esunas, so you can get a set up that applies to the difficulty of the content you're attacking.
If it was customisable to be able to tell the game "every time a cure card is in the deck, play it" then a lot of people would be able to grind more efficiently. I don't think the card colours matter for non-attack or magic cards (maybe for cure? idk I haven't tested it so it might tick someone off that Minnie is played before two red cards and their cure is smaller than it would be if it was played with one or two other blue cards, but in saying that I've had auto hold back a Minnie until I had more blue cards in my deck and then it decided to play an attack rather than the cure I needed soooooo idk, I'd much rather any cure than the "perfect" cure)
I also wish the timers for boosts were changed as well. Right now it just puts a 1, 2 etc. next to the icon depending on how many have been played and stacked, but when they're 10 seconds each then I'd much rather there be a countdown on display but that might just be me.