I have heard of people laying one coat down and baking it, then doing another coat and baking it again.(It makes for a real shiny and glossy look) You have never heard of this, or you just dont do it that way?
You are right, it can be done in several coats. The guy that did all my stuff only bakes the parts 1/2 the required time, then adds the next coat. My wheels etc. have 3 coats on them, metallic gold base, candy apple gold and then clear over all.
Never heard of anyone putting more than one coat of powder on. Clearing over it makes the color a little different too. If the guy that did your wheels bakes the parts at half the required time, then he isnt curing the powder. Even if he puts a second coat on and then cures....that base powder still didnt cure correctly. I bet the parts look really good and I bet they will last, but i gurantee that the coating isnt as durable then if he cured it properly. My guess the only reason he did that was to achieve the color that you wanted? Might as well have had them painted.
He is also adding 'thickness' to the coating which you are not suppose to do. Like i said though, if they look good and you are happy with them, then great. I have been doing this for a few years now, been inspecting different kinds of coatings for the federal govt for years now, and have had to take countless classes on surface treatments of metals and coatings. I hope that adds a little weight to my credibility.
I hope that doesnt come off as a flame or anything. I not the least bit disturbed by any comments positive or negative. Its always good to see how 'other people' do it and what others think.