In nature, pure symmetry is normally not present. The same applies to this work. Between each re-exposure there is a short period of time during which the situation is changing: the river keeps on flowing, the flower sways in the wind, the duck dives under water. I also take the photo by hand so the angle degree is never exactly 45 degrees.
The results of these small variations still surprise me. Just like in life many events happen in patterns, yet are slightly different every time.