If there is any rule regarding that, then please enlighten me as you seem to be monitor.
Moreover, if I do feel that the feasibility of the train's run is affected by extra stops, I feel I do have right to put my opinion via red flag. There should not be any fuss about that. Since, the timetable is made on imaginary terms, "imaginary" useless costs incurred due to non-feasible stops should be kept in mind, as well.