If you want to be a good product manager, continue to learn more about new and different ways customers will use your product. As much as you may design very specific tasks and use scenarios, customers will always find ways to use your product that you never intended.
Understanding these alternative uses will help to identify new markets, new ways to promote your product, and new distribution channels. It also can help suggest minor changes that will better support these new uses without detracting from the main purpose of your product.
Understanding alternative uses of your current product can also lead to brand extension and other new product ideas.
WD-40 and baking soda are two other examples of essentially commodity products whose continued success has been driven by an understanding of customer needs and uses for the products. WD-40 introduced their Big Blast can when they saw that customers needed a way to distribute the same formula over a larger surface area more quickly and easily. Arm & Hammer had long recommended baking soda be used inside of refrigerators and freezers for removing odors. Open boxes could easily be spilled, though, which led to the creation of a special non-spill version designed for use in refrigerators and freezers. Arm & Hammer has further extended their line of products, making new products tailored for distinct but common uses.
As a product manager, you need to understand and focus on the main purpose for your product — what the main value is and what markets you are serving. In doing that, though, you need to keep your eyes out for new ways your customers are using the product. This will likely give you clues into new markets, new promotional strategies, new product ideas, or changes to your current product to increase sales and usage.