I can imagine the advantages/disadtvantages of both systems.
If you have a system where you have 2 schedules to the end destination, one of them skipping most stations while the other as stoptrain (AH vs ABCDEFGH) then it would be nasty if the stoptrain gets filled with ppl wanting to go to H
If you have a system where schedules share a part of the same route and then go their own way (ABCDEFGH vs ABCDIJKL) it would be most beneficial that the farthest destinations get filled first.
I generally tend to use the 2nd system more than the first one so I would be in favour of this. However if it's something that could be set as an option of a line: support^2.