The dressage test makes sure that the horse is listening to the rider. It tests that the horse is very well trained. The cross-country course makes sure that the horse is fast and brave, since cross-country fences may be very scary. The show jumping makes sure that the horse is in good shape, since he must do it the day after running over the long cross country course or on the same day. If the horse is too tired, he will hit the show jumps and make it harder for the rider to win.