Bespoke joinery taught us something that applies directly to doors: consistency is harder than performance. Plenty of people can make one beautiful kitchen. Making the hundredth exactly like the first takes fixed jigs, an inspection at every stage, and accepting that you never trust the eye alone.
That is what we apply to the interior door: sizes held, a finish identical from one leaf to the next, and a work order that lets us know, six months later, which panel a particular door came from.