So I did eventually mess around with the circuit network. I didn't use your setup, mostly for lack of understanding at the time (I think I understand it better now). The setup I use is certainly more crude, but works vaguely as follows.

For each resource a train might load or offload, there are 3 ...

So the gist of my current setup is as follows:

I have 4 train stops, and 2 trains. There's an oil train, previously described, which is ferrying oil byproducts to manufacturing, and the necessary non-oil ingredients for those byproducts back, and there's a train ferrying ore from a couple places ...

As I said, I've not explored circuit networks in much depth, so there may be an easier way therein. I wouldn't be surprised if there was a more robust way to handle all the logic with the circuit network.

That said, the circuit network seems incredibly opaque to newbies like myself, which is part ...

I'll preface this by saying that I did some cursory searching, and didn't see discussiong of nested OR (which surprised me), but maybe I'm not using the right terminology to look, so I apologize if this duplicates an existing suggestion.

I'm somewhat new to the game, and I've been playing around ...