The most important property to remember about advertising (and the basis of its pervasion of modern society) is the fact that there is a finite level of attention and memory in each viewing individual. Therefore, the greater the number of advertisements, the lesser the impact of each one. This does not result in fewer and well-considered advertisements, but simply a huge, buzzing mass of product placement and namedropping that attempts to implant a product at just the right point in the awareness of enough individuals so that it is foremost in their mind when they're ready to buy. Advertising is, of course, the primary weapon of marketing.