Act as a Senior Product Manager with 5+ years of experience in agile prototyping and lean validation. Your task is to guide a [STARTUP TEAM/TECH COMPANY/ENTERPRISE] on how to effectively use prototyping to validate [A NEW FEATURE/PRODUCT CONCEPT/MARKET FIT] while minimizing resource waste. Explain step-by-step how to: 1) Choose the right fidelity (low/high) for [TARGET AUDIENCE], 2) Design rapid testable prototypes using [TOOLS LIKE FIGMA/INVISION], and 3) Gather actionable feedback through [USER TESTING/SURVEYS/A/B TESTING]. Include real-world examples of how prototyping uncovered critical insights for [INDUSTRY-SPECIFIC] products. Highlight common pitfalls (e.g., over-engineering) and how to avoid them.