This is something that, for some reason, has been bothering me ever since I got this game. The yards such as Cumberland yard seem very Lifeless. There aren't enough cars around the yard, not enough locomotives either near the shop or out doing switching. The yard just seems deserted at times and there isn't enough in it. So, I think there should be more Locomotives sitting around waiting for service or servicing, more freight cars just to make switching duties a bit more complex and interesting, and just in general more life in the yards. That would make the yard in Cumberland and in general all the yards through the whole game a bit more interesting.
this applies to GWR too - not enough hoppers strewn about and static etc, I hope one day for an AI slider as not all services are present in game, i wanna push mine to the max.
It seems to me this is old problems hurting new content. Before optimization, any more cars in Cumberland would kill the game, so they didn't put so many around. Now, the game can handle many more and get the same performance. As for switching services, DTG was not very used to them, tried to do some, but could not get them working in time for release. Looks like they never decided to finish the work they started on switching services beyond Q375's assembly...