As a design principle in general, balance is typically used in spatial terms. You wouldn't, for example, have all of your furniture on one side of the room. It’s not only impractical, but it also isn't very pleasing to the eye. It’s no different when mixing metals. Both large and small spaces should have a mostly equalized approach so that one side of the room doesn't “hold more” or appear visually “heavier” than the other. Blending warm and cool tones by dispersing a bit of each throughout the room creates an attractive visual flow and helps the whole space to feel cohesive.
This kitchen is an example of achieving the perfect balance of mixed metals.
