Every prototype is a question aimed at risk: will users understand this? Can we build it? Does it feel right? The craft lies in matching the fidelity to the question.
Paper sketches answer flow questions in an afternoon. Clickable wireframes validate navigation before visual design begins. High-fidelity prototypes test emotion, brand fit, and edge cases — but only once the structure is settled. Skipping levels is how teams polish the wrong thing.
Prototype the risk, not the product
List your three biggest risks — comprehension, feasibility, desirability — and prototype only those. A checkout team I worked with tested five payment layouts in three days and killed the pet concept of the CEO with data, not debate.
A prototype is the cheapest possible way to be wrong — and being wrong early is the whole game.
Treat prototypes as disposable by design: version them, test them with five users, harvest the learning, and throw the file away without sentiment. The product keeps the insight; the prototype did its job.