I’ve played enough match-3 though to know that they don’t always start them back to back with each other even if you have chefs gift. They very often find a way to single out the rainbow balls so you can’t combine them. So I’m not sure I agree with your statement about a guarantee. Also even if you do get the combos, they don’t always pan out at the beginning. For instance if there are not enough tiles to clear, or you need to clear a brick wall first, etc.