I like to run 25 to 30 cars, and 2 or 3 units. I have a couple hidden sidings under the layout, that will hold 25 cars and 2 units. If you want to run long trains, spend a few bucks for a coupler height gauge. I was amazed at how many ready-to-run cars had couplers either to high or too low. That is the major cause of uncoupling.
There’s a 30 car coal train getting ready to leave, in the center of the picture.

Good image Hobo! I like the way you have passenger trains stacked around that small station. Maybe you need that Mikwalkee road station and trainshed now huh?
I enjoyed that long coal train photo very much.
Speaking only for myself, I have designed my entire layout to handle 20 “car length equivalent” through freights with two 2-8-2s or equivalent catenary power. Through freight staging, visible sidings and arrival/departure tracks are long enough to clear that length, but no more. As good luck would have it, that is sufficient to accept my longest passenger trains with room to spare.
The reason? That’s the length my prototype was designed for, and the maximum length I saw running there in 1964.
And now for the joker in the deck. A “car length equivalent” is only 105mm over couplers - which I can get away with since the usual freight wagon is a 4-wheeler of 15 to 18 ton capacity. My 20 car freights are equivalent to 13 AAR 40 foot cars long, far from overwhelming on a 16 x 20 layout.
Chuck (modeling Central Japan in September, 1964)
I have 12 heavyweights and am building another passenger train of the same length and must accomodate them. That is in the future space. They can be run as they are today but have a bit of issue with the Observation car people watching thier own engine working behind them.
=)
Maybe one day I will take the set to another railroad with room to spare and let them exercise.
Actually I am in N scale because I have space restrictions, but I always liked N so I am fine with it. I do more in the way of operating than I ever did with my HO layout, which literally was running trains around for no reason. I actually have two points on my layout where switches come in and I base the train on how they fit between these points. Like I said I do push it a bit but I like the longer trains, and try to make sense out of the mainline run.
One thing I have done is have relatively generic scenery on my layout so it doesn’t have to represent any one area, but my railroad I created has several different types of areas that I can use for points of reference. If I could actually model this thing it would be amazing. But in a 6 foot area you do what you can.