Why is a percent yield important in chemistry?
In chemical factories, we don't always get the theoretically expectedly moles or amount of product(s). This is because the actual temperature required for the reaction to take place cannot be always provided and so a compromise is used. Moreover, the product might not be obtained in their right state. There might also be impurities in the reactants.
Hence, percentage yield is extremely important in determining the amount that could be obtained in practice.