After taking several thousand pics following the rules, I began to ask questions about those rules like a rebellious teenager. What if your subject was backlit by the sun? What if you shoot water with a slow shutter speed in bright light, or even with the sun shining directly on the water? What if parts of the image were so overexposed that those parts get "blown out", meaning the area is so bright the camera couldn't record data so it's completely white? Is it possible to make a pleasing image breaking all those rules? Is this too many questions? The answer to all of these questions is yes.
The image above breaks all the rules. The bright August sun was shining directly on parts of the water, with the sun upstream in the direction of the subject. I discovered a couple of years ago by mistake when shooting flowers that some images actually looked better with bright sunshine splotched on them. The blown out areas actually draw the viewer's eye to the subject and provide a sharp contrast to adjacent dark areas. The blow outs at the bottom of each plunge in this image are actually THE focal point of the entire image, the subject itself. With a little imagination you can visualize how this image would look without the blow outs if it were taken on a cloudy day. In my opinion it would be a much duller image, technically correct from a photographic perspective but more boring from an artistic perspective. The watercolor filter was applied to this image also and left very strong. By that I mean most of the time the filter is applied then the opacity or strength of the effect is reduced usually around 50% or more. In this case the filter at full strength enhanced the stark contrast between the light and dark areas and emphasized the texture of the rocks. I really like this image. Here's the normal image, shot 6/10sec at f22 with a polarizing filter (on a tripod).
The lesson for today is: learn the rules, obey the rules until you understand why they are rules, then blow them away and do your own thing.