I have a booth and paint a few times a year with a few different types of paints.
Laquer can be painted in many layers and is usually buffed or sanded between coats. It's an old style of paint and the paints of today are much more durable and give a better finish with less work in my humble opinion.
Acrylic Enamel or Base Clear are not usually painted in more than two or three coats because the paint will become brittle and crack the thicker it gets. Also, the drying time needed between coats as the layers increase would make a 16 coat paint job about a year long. The reducer needs time to come out of the paint. The top layer usually dries first making it difficult for the chemicals close to the metal to cure and evaporate. I can't tell you how many times I've ruined a paint job just by leaving it out in the sun too soon after painting. The radiant heat causes the reducer trapped under the top layer of clear to try and evaporate. As it does it causes orange peel on the surface of the clear. Or at least so I was told by the tech guys at PPG and DuPont.
I don't paint for a living, but I've never heard of a 32 coat Isocyanite base/clear paint job. The most I've ever painted is three base, two tinted clear, and two clear. Even with flexibilizer the clear cracked two years later on a plastic bumper in the winter. I can't imagine a 16 coat clear hanging let alone surviving.