There are a lots of decision-making steps along the product-development path. Those of us in the software industry who were influenced by Kent Beck et al talk about “spiking.” It means trying to build just enough of something to expose the unknowns that we would have missed otherwise. It’s not unusual to spike two different approaches to the same problem to see the difference in their characteristics.
These examples only scratch the surface. The big idea is to think of prototyping not as a single costly effort to build and verify a single guess, but as a way to learn, to uncover what we don’t know — to find the best way forward for the unanswered question at hand.
[Public prototyping also takes place… like with Constraints and Creativity. I did some prototyping privately, but there’s so much more to learn about the choices that sometimes it makes sense to do them publicly.]