When I was a recently returned Southeast Asia vet, and more or less starving to death in California, I interviewed for a manager's position with Color Glow, which was an Earl Scheib type franchise paint shop. Their quick production trick was a bunch of proprietary colors of alkyd enamel that "sorta-kinda" matched most of the more popular OEM color charts, and a baking oven to do a quick cure of the paint. They also didn't use primer or sandpaper. Surface prep consisted of an aggressive scrubdown with household ammonia and a Scotch-brite pad, a quick wash and dry job, and start shooting paint. I didn't bite on that offer, as I found out that there was a pretty rapid turnover of managers at that facility, and even as a hungry man I had some degree of personal integrity!
Jerry