If you want to limit the duration of a discount on a child product's price,...

To limit the duration of a discount on a child product's price within Salesforce Industries CPQ, you would use "The time plan on the child product's discount." This approach allows you to set specific start and end dates for the discount, directly linked to the child product. It provides a targeted and efficient way to manage promotional pricing on a per-product basis, ensuring that discounts are applied within the intended timeframe without affecting other products or overarching promotions.