Lassy, are you sure your analogies are actually accurate?
I'll admit, I do feel(I think we all do) that there has to be practice in order to get better. But isn't sss the exact same thing as ppp?
BUT you mention two activities that are predominantly physical. In sketching, yes, the mind/eyes need to be able to see the sketch to be sketched, but as in shooting, the actual execution is a physical act. So to put it simply, muscle memory is trained and dexterity is developed and trained into the body. A long lapse in those physical movements results in deterioration of the skills.
Photography is purely cerebral. It can be done and carried out at the highest levels by individuals having virtually no motor control whatsoever. It's purely the mind that is being trained to perform and having the knowledge to set up a shot, as in commercial, where extremely acute knowledge of lighting is acquired, but a photographer can actually give instruction to an assistant to set up a shot, as Julius Shulman did in his later career. It would be virtually impossible to instruct another to sketch a masterpiece.

I guess what I'm saying is, in photography we can only practice effectively after we have learned cerebrally what we are trying to practice/execute onto the camera sensor/film as an image. there is no motor control needed at all by the actual photographer! ;-)
SS