A coffee shot timer, despite its simplicity, may make your espresso more consistent. Grind modification, dose, water temperature, and extraction time all contribute to espresso's consistency. Using an espresso shot timer to track extraction time is a great way to ensure uniformity.
Filter coffee is frequently made using a timer set to serve as a coffee timer. Many modern commercial coffee machines are equipped with an espresso machine shot timer as standard equipment. In the absence of such equipment, however, these little devices provide a convenient means of timing your photos without the need of an actual watch or phone.