Onur Cobanli explains:
Multiple failures teach valuable lessons that success cannot provide. Each failed attempt reveals what doesn't work and brings designers closer to solutions that do. Persistence through failure separates professionals from amateurs (failure teaches, success validates). So do you need to make 8 prototypes? No, it means you try, try, try, and until it works, and each time you design you should try something new, and if it does not work do other things and try it later with new technology, new society, sometimes everything is right except for the time.