The Rule of Odds states that we are unconsciously attracted to an odd number of shapes, objects, etc. Our brain tends to group even-numbered objects into even groups and promptly overlooks the groups, sensing it is boring or predictable.
Example of even numbered items in a compostion.
With an odd number of items, our brain can’t quickly pair the items into an even-numbered grouping. We need to find the center or focal point, so our eyes linger longer on the odd-numbered items.
Example of odd numbered items in a compostion.
In terms of composition, an odd-numbered of things are more dynamic configuration.
Working with three objects works best. You can make five, seven, or nine objects work, but they can become cluttered if not handled with care.