This is so that the work can be failthfully and loyally reproduced. If we do not recreate the specific sound, we are being unfaithful. The works logical stuture. The piece must move forward. It must move through time, this is not clock time , it is the time of the heartbeat, a sensual time.
Conductors are recreative artists.
The work's history. The composer's history. Date the work was written and published. The title can be a guide to its form, therefore suggesting a style and shape. Look at the end of the composition to see where it is going.