What is the maximum time allowed before a good double shot can no longer be used?

The maximum time allowed before a good double shot can no longer be used is 30 seconds. This time frame is crucial because once a double shot has been brewed, it begins to oxidize and lose its flavor profile. After 30 seconds, the coffee may start to develop off-flavors and the crema can diminish, leading to a less enjoyable and less consistent experience for the customer. Maintaining this time limit ensures that the espresso served is at its best quality, optimizing both taste and aroma. This is common practice in specialty coffee preparation to guarantee that customers receive a fresh, rich espresso with the intended characteristics.