Tip by Scott Vanderkolk from Indiana.
We place a heavy emphasis on serving efficiency and being aggressive with our serves. Early in my coaching career, I noticed that one of the biggest reasons we were missing serves was because we were tired and not mentally focused when we got to the service line.
To combat this issue, 2-3 times a practice, we utilize what we call "Serve 10". The concept is simple, serve a ball, chase it down on the other side of the court, and serve again in less than 5 seconds. This gets serving reps and conditioning taken care of in one simple drill.
A variation we use is "Pressure Serve 10". The drill is the same, but adds a burpee before your next serve if you missed the previous one. Each subsequent miss results in adding a burpee for each miss. Another variation would be using specific zones or short serving depending on skill level.