The Adjustability Exercise
Generally a good, smooth, clean show jumping round happens when you have the right quality of canter, and your horse is adjustable between fences. If your horse is lacking in adjustability, it does not matter how great the canter is that you start off with - as you will find that the quality of your canter will likely diminish as your round goes on. And because your horse is not easily adjustable, you will probably be unable to truly fix it while on course.
First of all, what do I mean by the right quality of the canter? The right canter to jump out of is balanced, rhythmic, straight, and in self carriage. With the appropriate amount of impulsion for the jump in front of you.
It takes adjustability to be able to maintain that canter throughout a course. Your horse may approach the first jump with the right canter, and land from the first jump running, flat, and out of balance. If your horse is adjustable, you can easily put him right back in the same quality canter you had before the jump. If you do not have adjustability, your rounds will tend to get worse and worse as you go on.
Here is a great exercise to improve your horse's adjustability: (Click on Article Title above (in blue) to read full article)