I like to paint my shells with whatever I have left over in the spray gun when I paint a car... I can usually prep them in the time i wait between coats. But they only end up 1 color and the window masks are not usually very straight. I do agree, and often run the shells clear if I really want to get a run in.

As far as time and movement are concerned, there would be no time if there was no movement. Distance is very important as well. Time is based on movement over a distance, where the distance is fixed. At least that is how it works on our little wrinkle...