I'm with Hot Water and Wyhog. The employee timetable listed the regular stops for passenger trains, and for the top tier of trains, they would often only make one, possibly two, scheduled stops per crew district (100 to 150 miles). There would also be a special notation to the effect that "No. XX will stop at XXXXX to discharge passengers from XXX and beyond or to board passengers for XXX or beyond." They only made those extra stops when there were passengers who qualified by that notation, which was not necessarily a daily occurrence.* These were called conditional stops.
There were also flag stops, indicated in the employee timetable by a letter f next to the time shown at that station for that train. The Engineer would approach the flag stop station, prepared to stop if flagged or to pass without stopping if not flagged. The Agent or Operator would flag the train for passengers. At stations where there was no employee on duty, a flag and instructions would be provided for passengers to flag the train themselves. However, in my experience, the premiere trains (when they really were premiere) did not make flag stops.
As secondary trains on a given route were discontinued, the limiteds often became less so, as they picked up the head end business and some of the station stops of the discontinued trains.
* If there was a passenger on board to be discharged, the Conductor knew about it and, after passing the station in advance, would sound "Stop at next station" on the communicating whistle. If there was a qualifying passenger to board, either the Conductor's manifest would indicate it and he would advise the Engineer via the communicating whistle - or - the Conductor and Engineer would receive a message with their Clearance Card advising them that a passenger would board at the specified station.
Tom