Film critics see film making in three discrete steps. First being screenplay when the script and its flow is decided. The next step is cinematography, where the film is actually shot, with actors being the medium. The third step is editing, where the film is made presentable to the audience. It is however, the director, who always carries the complete picture in his head, and makes these discrete steps merge.
This is the reason, many great directors have often worked hard in refining each steps, without loosing the big picture. Kurosawa, for instance, worked very hard on the film’s script. He often collaborated with a group of five screenwriters, all of them would gather around a table, and work on exactly the same pages of the script, and Kurosawa would choose the best-written version from the different drafts of each particular scene.
Ingmar Bergman gave cinematography the highest priority- the very reason that they were so beautiful and poetic in nature. He never experimented with cinematographers. He was known for his constant collaboration with the cinematographer Sven Nykvist. Such was the talent of Nykvist, that Bergman, on the morning of the shoot, would briefly speak to him about the mood and composition he hoped for, and then leave Nykvist to work.
Stanley Kubrick heavily relied on editing. He believed that everything else in film comes from other aspects of art. Writing, of course, is writing; acting comes from the theatre; and cinematography comes from photography. Editing is very unique to film. This was precisely the reason he used to shoot each scene in a large number of retakes from different angles. No wonder this often made his actors angry who swore never to work with him again.
These directors, took each step as a continuous part of the directional process. They never considered scriptwriting, cinematography or editing as separate from direction. If film making was a discrete process, skilled directors like Kurosawa, Bergman and Kubrick would have ceased to exist. Film making is an art. This analogy itself makes it free from following any steps or algorithms.
An average director sees good script. A legendary director visualizes the the frames being edited when the script is being read. That makes all the difference.