In a close study you do not need to try to make a perfect reproduction of the original. The brush is not a camera or a photocopy machine. Thus, no one can make an exact reproduction of even a single line. We are human beings, and each line we draw is slightly or vastly different from another line we draw. Rather, drawing each line in a close study is a process of learning as much as possible from the original. This is the ultimate way of training with calligraphic discipline, in which the process can continue for a lifetime. Each time, we learn something new.
There is a wide range of calligraphic study you can conduct. You can be highly disciplined at one point and be completely free at another. Your disciplined study can be strengthened by your free exercises and vise versa. Discipline and freedom are the two feet of creativity. The most effective way of developing creativity is to alternate these opposite exercises.