As with the last poster, my experience is with Automotive 2-pack.
I have to add that an aquaintance, with the cooperation of a qualified Engineer, stripped and repainted his 172 at his own body-shop, using Sikkens automotive paint (Autocryl)
the hardener is of paramount importance and a graduated mixing-stick,together with a parallel-sided,flat-bottomed,small-radius-cornered container ,are also crucial to accurate mixing-ratios,in the absence of digital-scales and fresh, correctly-stored materials.
Mixed and applied correctly this paint-system is extremely tough,glossy and resistant to UV, chemicals and weather.....it is little short of indestructible.
The downside is that the resin carrier and catalyst are isocyanate-based and breathing-apparatus is a must. breathing the cyanide fumes quickly leads to all sorts of respiratory problems.
yes, the paint will DRY....but without the catalyst, it won't cure and will have a durability approximating Dulux.
OK, you CAN touch-in the odd chip,with just the paint, but it's not hard to count the appropriate number of drops from the mixing-stick (3paint, 2 hardner,1 thinner, IIRC) stir together with a lolly-stick or screwdriver, dob-on with a cocktail-stick, cure with a hairdryer in 5 minutes
This stuff is like liquid Araldite. Air-drying paints work by reaction with the Oxygen in the air (oil-based /coachpaint) ,or evaporation of the solvent (cellulose) I would not go back to either for auto/marine/aviation
You MUST clean equipment immediately and thoroughly after use,- a half-full spraygun will contain a block of jelly after about 3 hours at normal room-temperature......at 12 hours it's probably "potted" solid.....same with brushes,mixing-sticks etc.