There's more too it than just putting ink on timetable. The host railroad has to agree to every stop, because in theory a train could stop at every town listed on the timetable. It'd be like getting Tri-Rail to agree to let Amtrak stop at every station its corridor, it slows Amtrak down which can create flow problems for Tri-Rail. In areas where there are no stations a platform must be put in, parking lot, shelter, etc. Also remember that creating even a flag stop, time must be budgeted in for each stop, more stops = slower schedules, slower schedules = less attractiveness to take the train as far as time concerned. Remember some people can't wait to get off the train from NYP-MIA after 24 hours, piling on more time doesn't help anything.