ibranz,
Storyboards are an excellent tool to use in creating a structured and ordered flow of information with a clear "beginning," "middle," and "end" as you explain, whether for communicating a focused marketing message such as a television commercial or delivering the plot line of a story (as sometimes used in feature film production). However, in my opinion, creating a storyboard when discussing such a "global" topic as a company "brand" is a bit like "putting the cart before the horse."
A storyboard can be an effective aid when developing one of perhaps many "tactics" (such as a television commercial, YouTube video, or perhaps in some manner as you suggest, as a Web site "navigation chart"), where these tactics would be utilized to help execute and support an overall marketing "strategy" to drive sales. Unfortunately, I'm not able to see how using a storyboard would be an efficient or effective tool to discuss your friend's overall company "brand" as you have stated the situation.
To me, it seems you are using storyboards to show abstract intellectual concepts (like that of brand perception) in a more tangible manner by illustrating them on a storyboard, which is probably good whenever abstract concepts can be made more tangible, but it seems to me using your technique adds in an additional element of abstraction (your ability to accurately illustrate the perception by the target market of your friend's brand in the first place on a storyboard, then a potential additional abstraction doing the same for his competition). I'd say an easier way would be to compare actual sample ads (Web sites, print, video, audio, whatever) that your friend's company and his competitors have produced, side-by-side, then examine your perceptions of "brand."
I would want to make things as clear as possible when dealing with an abstract concept such as "brand," and eliminate as much as possible any room for "differences in individual perceptions" that may be introduced through your "interpretations" of brands by illustration. I would think your friend would need to be highly sophisticated in conceptualizing abstract branding concepts, and further to be even more sophisticated in understanding how you are using a linear, time-based graphical device to depict abstract psychological concepts. I would not advise others try this sort of technique except in very unique circumstances (which you may actually be describing though that's not clear from what you've written).
For example, if I were to comment on a particular company brand in the manner you suggest (really, an advertising comparison), I would want your friend to look at the overall "image" of his brand (or product, or company) in the mind of the target audience (in a very broad sense, what the brand "means" to those who exchange their money for his products). Then, I would compare and contrast your friend's company's brand image with competing brands or alternatives. This could most accurately and easily be accomplished through a direct comparison of advertising materials and other promotional efforts, directly, from your friend's company and the competition, side-by-side.
I would then go an important step further and compare all this to your friend's company's strategic plan to try to determine if the brand image established with the key target customer matches the company strategy. Doing such a brand analysis with a storyboard seems highly unorthodox and of little practical value to that end. If you mean that you are actually doing a super "quick-and-dirty" competitive advertising analysis by illustrating actual samples of your friend's and his competition's advertising efforts on storyboards, primarily because you don't have samples of these materials handy, then maybe it would have some value in a very broad sense if it started a productive dialog leading to some serious brand analysis, but it's not something I'd want my friend to bet his successful $2.1M business on.
More appropriate I believe are techniques that can very easily be done, say, on a paper napkin at lunch and be, in my opinion, significantly more effective as a quick-and-dirty brand overview. One "paper-based" technique I have used to help define a "brand" for a company is to map out brand positions on a what might be called a "perceptual space map," where you plot the relative position brands lie in regards to the target customer's perception key product attributes. Say for example, that your friend's company has as it's key strategic initiative to establish a brand image in the mind of a specific target market segment that its product is a "high-value" product, with "high-value" defined as "very high-quality and easy to use." To plot this on a "perceptual space map" you could draw two axes, say with the vertical line (x-axis) representing ease of use (difficult at the bottom of the axis, easy at the top), and the horizontal line (y-axis) representing quality (low quality to the left, high quality to the right), with these lines intersecting at their mid-points (forming a cross or large "plus" sign).
Then you and your friend could examine the perception of your friend's product and mark on the vertical line how easy the product is perceived to be to use, then mark on the horizontal line the perception of its quality. The point representing the intersection of those two plotted points represents the perceived "value" of your friend's product.
If the intersection of the two points falls in the upper right quadrant of the plot, the product would be deemed as both easy to use and of high quality, and thus a perception of "high value" to the target market. If the point of intersection falls in any of the other three quadrants, it would not meet the stated company strategic objective which would be the case when:
1. in the upper-left quadrant where the product is perceived to be easy to use, but of low quality (fix this by improving quality);
2. in the lower-left quadrant where the product is perceived to be both of low quality and difficult to use (fix this by improving quality and ease of use);
3. in the lower-right quadrant where the product is perceived to be of high quality but its difficult to use (fix this by making it easier to use).
An extremely simple, convenient, and effective technique.
Many others "paper" techniques can be used to do a similar crude "brand analysis," but I'm not sure how useful information regarding "brand" could be achieved through using a storyboard in the traditional sense of how a storyboard is used.
If you are using the word "brand" more as a "verb" to refer to a particular technique (tactic) to create a desired perception of an existing brand through some form of communication that changes over time, then I can certainly understand how a storyboard would be most useful as a simple shortcut method to explain how that tactic might be executed. However, my understanding of the word "brand" is more as a descriptive term ("noun") that would better be explained using other more appropriate techniques.
So, I guess I need to ask the question directly: are you using the word "brand" as a verb? If so, suggesting to illustrate the "branding action" implied by the verb "brand," in a sequential linear form, that changes over time, as represented in each subsequent frame of the storyboard may make sense, otherwise, it seems makes little sense to do so (unless you have some storyboarding technique I'm not aware of, and I've seen many).
In any event, I agree that taking a thoughtful look at the image your company communicates to the marketplace is important, and I agree that adopting the viewpoint of the customer is critically important (my buzz-phrase has always been "think like a customer"), so anything that leads to that end will probably be of some benefit, but not all analysis techniques are created equal, and your own mileage may vary (significantly!).