Ronald Koeman's famous ("terribly boring") warm-up
このエクササイズは、Ajax Training Sessionsで文字通り"warm-up"として紹介されていて、
Ronald Koeman's top ten most used drills, 2002-2003: (based on my counting) に選ばれてます。
Player A passes the ball to player B,player B receives the ball with his left foot and passes to player C with his right foot. Players rotate after each pass.
と、ここだけ読んでしまえば単純なドリルですが、
The drill is all about receiving and passing with the correct foot and with the correct speed. Also player C has to call for the ball at the proper moment (just before B receives the ball).
と続いていて、これは紛れもなく「判断を伴うトレーニング」です。