In a very real sense, each horse has a finite number of good jumps in his lifetime. You have to always, always be aware of how many jumps you are using up.
In other words, if your horse has one million jumps in him, every fence you take means one less fence you can jump later. Therefore, it is critical that you use those jumps wisely. Make each one count. Geoff Teall on Riding Hunters, Jumpers, and Equitation: Develop a Winning Style (via vagabird)