Early in my career I have learnt the importance of prototyping well before venturing down doing a full implementation of an idea.
While many prototypes we built have never been commercialised. Prototypes helped us to incrementally increase our skill-set & bring in new ideas. Many of them today are being transferred into commercial work we do for others & products we build.
In this TED video Tom Wujec demonstrates Marshmallow Challenge. In essence how prototyping makes better products.