Satisfactory it’s honestly just easier to treat it like a conveyor - by that I mean there is a constant flow in and out, the train just buffers that. Like how we think of the internet being a constant flow but really it’s a series of buffers
I usually plan for a train car to get about 1/2 full while it waits for the train to come back. I don’t remember how many stacks that is, but of course you don’t want to car (buffer) to fill up and then you’re constantly behind.
I usually run my trains at 2 engines followed by 10 cars, that’s usually a very good amount where you can standardize your stations, and give you plenty of room if you fill one car there’s usually another free car on the train to add on to.