One disappointment I tend to have is the end of the chain tends to be one store somewhere. Really, if you have, say, textile, cars, gasoline, &c. you'll have one or more store in any substantial town within reach ... those endpoints likely sell a variety of goods from different chains: books, processed food, textiles, fruits, veg, &c.
This can get very complicated very quickly, if you have, say, three chains that end up in a dozen stores each, some with overlap. You would set up a warehousing system ... maybe goods leave the factory by rail, dropped at regional warehouses, then truck to the nearby downtowns ...
Now, you have the problem of "wait until full" &c ... your warehouse stops .. a warehouse could easily be serving 3-4 ... even a dozen endpoints if multiple classes of goods are involved, which would mean a bunch of loading bays and then long roads leading to those loading bays for when trucks line up to wait for goods that aren't available ... &c.
In real life, the trucks would pull up to the warehouse and the dispatcher would send them out to whatever stores were awaiting delivery. This is not the Simutrans way.
I thought about, how WOULD you do this in Simutrans within the existing route framework, and my thought is a new feature could be "skip stop if no cargo."
So, now you could have say, a route like so:
Town A (skip)
Town B (skip)
Town C (skip)
Town D (skip)
So, if you are on this route, you go to Warehouse: load goods .. do you have any goods for Town A? No? Skip to next stop .. Warehouse .. load goods ... do you have anything for Town B? No? Skip ... do you have anything for Town C? Okay, head on out ...
Would need to handle the case "all skip stops are skipped so I'm just routed in a circle" thing which could be a race condition in code.
This would also enable "flag stops" on passenger lines: if there are no passengers waiting to pick up or drop off at a stop, the vehicle needn't stop. Could save trouble in cases where the flag stop is a monument which is a detour from the main road ... if we wanted to maybe put a "waypoint" before the skip stop so the vehicle doesn't decide to skip the stop until it gets to a particular junction on the way to the flag stop.
Lots of creative possibilities .. trains could maybe turn around earlier to serve a busier part of a line instead of deadheading all the way to a small town at the very end ...