Bresson’s idea of a decisive moment or how you achieve this does not have a science. Theres no organized thinking or force structure in creating this. When taking pictures in a active, lively moving world, the elements and or objects may be chaotic at some points. But at the right moment everything will be in harmony and everything aligns naturally in the frame. How to know this moment is an instinctive thing. Theres no wrong or right way to accomplish this.