Prototyping is essential for resolving usability issues before launch. It can also reveal areas that need improvement. Once a draft of your product idea is in the hands of real users, you’ll finally see how they want to use the product. You can then go back and adjust your initial guesswork.
I use prototyping a lot in my work flow. One of the most common misconceptions about prototyping is that it only needs to be done once or twice at the end of the design process. This is not true. I would say “test early and test often.” One of the popular phrases from IDEO status that "If a picture is worth a thousand words, a prototype is worth a thousand meetings"