The length of a product tour should match the complexity of the product and the needs of the users. For simpler products, a quick 2-5 minute tour might be perfect to hit the highlights without losing attention. More complex products might need a bit longer, up to 10 minutes, to cover all the bases. The key is to focus on what users really need to know to get started, cut out any unnecessary details, and keep things clear and logical. User testing can help find the right balance, ensuring the tour is informative but not overwhelming.