I'm going to go for a mix, I appreciate this is not quite as efficient but I'm okay with it.
I'm planning on building a station city in one system building everything, but I'm going to use a mix of medium factories, so for example a shield component factory, hull part factory, drone component factory etc, with each factory being self sufficient in its parts all the way back to the raw materials.
I know this will double up or probably even triple etc on some of the base productions like graphene etc but I think it'll be cool.
The system I'm setting up shop in is family Zhin, which I've taken from the Xenon who in turn took it from the ZYA and which in my game has every raw material in the belt, bar Ice, which is next door. It even has nividium.