One coat or many light coat?

I do armors only.  I do not apply just one fat coat of paint at once except for applying primer paint.  For the base paint, I'd thin the paint about 70/30 for airbrushing and make two or three runs.  I do pre-shading so the final coat will be highly thinned about 50/50 and do as many runs as possible until I am satisfied to see the pre-shades.  I use MM enamel and they dry pretty quickly in minutes before I can do another run or not.

I find that gloss paints are (generally speaking) a little more translucent than their flat counterparts. This is often more noticeable when using reds, whites and yellows.

General rule of thumb is to apply several light coats to build the required opacity and then (with gloss paints) apply a "wet" coat for the desired finish.

A single heavy coat is an invitation to problems like runs, "orange peel" and in the case of rattle cans, "honeycombing" from the propellant outgassing within the layer of paint.

For gloss paints, I do something in between several light coats and a single heavy coat.  I usually use an airbrush. I start with a very light coat to let the paint get a tooth into the primer.  I wait a minute or two, leaving compressor running (if I have gear doors and stuff not yet on model I do these and then go back to major assembly).  I then put on a heavier, sort of medium coat.  Again, relax for a minute or two, and then go back and put on a glossy (heavy) coat.  If the results are good, I am done.  Of course, occasionally I get a glitch, and have to sand it out and go back for another heavy, wet coat.

I sometimes use the same technique for flats- it works as well and is easier because the paint dries faster while I am waiting.  BTW, I use Testors enamels almost exclusively.

...many light coats...

No argument

Unanimity

Many light coats

Thank you all

I'm not sure I am in agreement, at least when it comes to gloss finish.  While it is good to put a couple of light coats on to get a tooth into the primer, if you really want a glossy finish the last coat must go down very wet, which means thicker.

Or a final coat of Future...