I think some confusion has taken place in this thread, the initial question of the OP is the painting of the "jambed" areas with a SINGLE STAGE paint, then finishing the outer body in a 2 STAGE FINISH, which often results in a slight color and or sheen/gloss texture change either right after painting or as the finishes age, GYC has termed this "El Cheapo" technique as "Pre Painting" as if it's something new,...it's been done for decades by cheap painters/owner who don't want to "waste" 2 stage, or the time of applying clear coat in the "jambed" areas...

Frankenberry I'll take you thru my procedure, 1st whatever paint is being applied to the body is used THRU OUT the entire structure, EVERYWHERE...after the vehicle has been bodyworked and primed and blocked to death, I'll remove the hood, doors, trunk lid and any other panels that have hidden areas, all the jambs, backsides,the interior,engine compartment, flanges, tabs, etc, etc are painted, then the panels are hung back on the car and realigned, then backtaping and aperture tape is applied in all jambed area to create a soft spray edge as well as a blending line for the outer body paint and the previously jambed areas so that after the body is sprayed the transition of the outer body painting blends into the jambed areas with little to no noticeable sheen difference, which can be polished with no effort later when the outer paint is cut and buffed, if a jambed area can be painted while doing the entire outer body then do it at the final painting session,but basically when I'm in the final painting stage, all the panels/doors/hood/trunk/etc are in place in the closed position with backtaping and aperture tape in place, when I'm done with a vehicle, it has the same gloss/texture and color thru the vehicle, there's a lot of masking, backtaping, aperture tape, papered areas etc, but when it's done it looks like it was painted all at the same time with no exposed/unpainted areas unless they were intended as such, as in an OEM underside application/finish

Mike