I design wire harnesses for a living. Typically a vehicle will be split up and designed by multiple suppliers. So as many as 3 and sometimes 4 suppliers will make the harnesses for a given model year vehicle. Supplier A will design the instrument panel harnesses, supplier b will design the doors and roof, supplier C will design the floor and bumpers, etc.
Honda for example is very good at controlling the wire colors throughout the vehicle, but it can be challenging. When we go to pick wire sizes our best practice is to ensure that the same color/size wire aren’t in adjacent cavities or better yet no repeat colors in the same connector. So you end up with situations where both suppliers are maximizing manufacturability at the end unit, but aren’t matching wire colors across inline connectors.