Fluther artists: Will you answer this color question (See details)

As you may know, I’m a watercolorist. One of my early teachers said not to use a color only once in painting, so for example, if you have a spot of red somewhere, it should be someplace else as well. The teacher I have now is always suggesting I put a spot of a contrasting color somewhere in the painting – perhaps a red bird, for example – to contrast with all the greens and blues in a landscape. But usually only in one place.

Obviously, I don’t need to follow rules and can do what I like – and usually do, but I’m interested in hearing from other artists as well.

Your thoughts?