The purpose of the follow through drill is to over emphasize the follow through until it becomes an automatic part of the quarterbacks throwing motion. As the ball is thrown, continue all the way through with your throwing arm and slap the wall with his right hand. When following throw with the throwing motion talk slapping the wall with the throwing arm and hand, this keeps the quarterback's throwing arm from coming across the body. As the quarterback releases the ball he should start his follow through, his right foot should slide forward.
At the completion of the follow through, the toes of both feet should be about two feet apart. The quarterback should finish up in a squared-off position which, in addition to aiding his follow through, it will also enable the quarterback to react quickly to dodge any linemen who still may be trying to hit him, or to make the tackle on any defender who may have intercepted his pass.
Courtesy Coach Jerry Campbell