A timetable will also have some extra time built in to allow for general small delays which could hold up a train on a routine basis. In that case running right at track speed can put you at a station early even if you left a minute late from the previous station. There are a lot of variables that can determine that, such as the length of a train, a doubleheaded train, and skill and experience of the engineer. It is unprofessional to speed over the railroad just to pull in on time. A good deal of skill is required to run a steam locomotive over varying grades and maintain a constant speed, and that comes with experience.