Not best, but optimum Transmission?

I rebuild these, and I'm shocked by how many people think a trans can operate just fine while it's low on fluid. They understand that it's a hydraulic unit, but think it's like a motor (which can run with NO oil). Their motor still runs when it's three quarts low, so why not the trans? Because the trans sucks air and burns up. Some think they don't have to have ANY fluid in it if it stays in Park. "Do Not Overfill" means so far up the stick that the spinning drums can aerate the fluid. Probably half of the transs that come in were destroyed by low fluid level. I've seen plenty of transs "20%" low that took a gallon to reach the full mark. I would overfill it half an inch.