One reason I use sprayouts is so I have a library of the different alternates. Next time I get that color, I pull out my sprayouts so I know what I have. I used to do one on every single car, but I have gotten lazy, plus I don't do near the volume I used to. I just spray the cards like they are, which are black to white, and note how many coats it took to get decent coverage. This can help knowing if I will have to spray an extra coat or two to cover a primer spot, without solely relying on my eyes in the booth.