The total number of finished books needed. Because of the process of printing the forms, folding the forms, gathering and binding, each step causes a certain amount of wasted sheets. A press is capable of running at a top speed of 9000 sheets per hour and prints both sides of the press sheet at the same time. A typical job can be as few as 200 sheets per form to as many as 5000 sheets per form. Also, a job may have as few as one form to as many as 30 forms.
Quality is essential.
Good press sheets must have consistent, even inking across the sheet, as well as from front to back. While the press is running the pressman pulls 1 or 2 sheets out of every 50 or so sheets to check quality.