So characterization has to be done very early in the process of creating a story. Also during the process of writing and rewriting, a concept can be constructed which will prevent the story from going in all directions. The plot driven approach sometimes works. You arrive at a concept, hammer out the plot of a good story, then start constructing characters that have exactly the characteristics needed to react as the plot dictates. I think highly skilled writers can do this.
Studios can get endless rewrites that slap together appealing characters.
But the proof that it can consistently be done successfully is lacking. Too many movies that get made, or stories that get published, just aren't very good. I think most writers can't create characters that will interest an audience using this approach. In the seminar we go deeply into creating characters. The goal of learning about characterization is to gain proficiency in creating well motivated characters - characters that will engage your audience.