Without product testing, you don’t know if each individual product component complements the others, nor if they are working in harmony – i.e. How you expected. Time, money and resource can be wasted in the further development of a product that isn’t fit for purpose.
Take food for an example. If you went out for a meal to a restaurant, you would expect the dish you’ve chosen to include ingredients that combine and complement to make a specific dish, otherwise the resulting dish won’t be as described or taste as you expected.
Pineapple on pizza?
We will leave that to you to decide.
Chefs and restaurants practice and test their creations, before it is added to a menu, to make sure that every ingredient complements each other and ensures it works, not just once, but every time it is served!
The same applies for a building system. Your materials needs to combine with other components in order to work successfully as a whole, otherwise product and system failures could occur.