How to design a prototype to fit the project approach (Builder.com) -- "My friend says that you want to get as much value as you can as quickly as possible. He advocates spending very little time on a prototype, so that you have wasted as little time as possible once the prototype is thrown away. I advocated spending more time on the prototype and possibly using the prototype as the basis for the actual solution. What are your thoughts on the question of how much effort to apply to a prototype?"