If the elements of the product and advertising are complex in themselves and essential to the realisation of the idea, additional efforts may be required for their development. To do this, we will return to the idea stage, and then check. In fact, we will consider such an element as a separate idea (sub-idea).
For example, you are building an online wallpaper store. You formulated and tested this product idea. Now, during development, you want to develop a calculator for the required number of rolls as a part of your service. How should this calculator work to make it convenient for the user?