There is a lot of flexibility with this unit. Following Rief's beliefs, I too agree that sometimes the personality of the class dictates a more structured approach or less structured approach. My students are often eager to start their own advertising projects, therefore, I spend no more than a week going over examples and techniques. During the three workdays, I may spend five to ten minutes doing a mini lesson that covers some other interesting facts about advertising. Overall, I devote about two to three weeks on this unit.
Rubrics are very helpful in grading their commercials.
Depending on what aspects of advertising you choose to cover, your rubrics are likely to vary. I like to brainstorm with my students as to how they should be graded. We look at the criteria I expect them to include and come up with points that are reasonable. An example of a rubric that I have used follows this article. The rubric is then posted on the board for them to use as a reference.