I'm not sure how strongly that works in a flower top, but in a vegging plant, the top shoot releases hormones called auxins that suppress side shoot growth. This is called apical dominance. To break this dominance, you can pinch the highest tip on the plant, or bend it down below the level of some side growth, and this will allow the side growth to bush out.
Don't pinch less than 3 weeks before inducing flower.