The question sounds logical, but the need for assessment, and even reassessment, occurs throughout the product life cycle, even at the end. There are a couple of important factors here. First, the bulk of smaller enterprises don't conduct formal evaluations during the idea generation or research and development phases of the innovation process. In contrast, the vast majority of large corporations do. Generally speaking, the further a product has penetrated the market, the more expensive it is to correct problems.
Product recalls are no fun.
Second, just because a product has been successfully marketed, doesn't mean it is ready for the big leagues. Sophisticated buying organizations, which include most national level buyers, typically have much higher expectations than smaller local or regional buying groups. In addition, their requirements are different. For example, packaging requirements are frequently simple and limited to protection issues with electronic and mail order buyers. However, with mass merchandise buyers, promotional issues are generally paramount.