Order of Production and the possibilities of sub assemblies

A question has come up for me regarding order of production for parts versus the main production line. I’ll pick on doors and power windows as an example.

Right now the main production line is:
Door Panels -> Windows -> Wing Mirrors.

When you get power windows you have another part (servos) that needs to be dealt with at the Door panel stage (I for get which). Which (of course) affects the main production line.

The question is this: Do we want to have the option for sub assemblies which are then stocked at door installation (Doors and Doors with Servos). Then the production time at the Door step is not affected, but you have to have a sub assembly station that works on the inventory conveyor to pre-prep this part.

I could see this also working for wheels/tires. If you have a pre-prep station for wheels and tires that assemble them into a component then the main line only has to install “Complete tire”.