The Rule of Odds states that we are unconsciously attracted to an odd number of shapes, objects, etc. This is because our brain tends to group even-numbered objects into even groups, which the brain tends to overlook sensing it is boring or predictable.
With an odd number, our brain can’t quickly pair the items into an even-numbered grouping. It needs to find the center or focal point, so our eyes linger longer on the odd-numbered grouping. This also makes odd-numbered elements are more dynamic in terms of composition.
Working with three objects works best. You can make five, seven or nine objects work but if not handled with care it can become cluttered.