The Reggie Miller 3 point basketball shooting drill is going to work on coming into your shot in transition, along with conditioning. As a player begins to get tired in a game, they are more likely to lose focus when coming into their shot and their shooting technique begins to suffer. This almost always means that they are going to miss the shot. For this drill you are going to practice shooting the basketball when you are tired, which will help you develop the player develop their shot, but also teach them to be mentally tough and learn to hit a shot at the end of a game.
It is also a good basketball drill to put pressure on the shooter, because on the miss they have to do more running then if they make the shot. The key is focusing on the next shot and having a short memory.