How do riders, trainers and judges account for the difference in horse abilities in a competition based on catch rides?

Students who compete on an Intercollegiate Horse Show Association team know the drill. This weekend, the horse that you show makes equitating a bit difficult. It drags you down the lines but has a stride the size of a postage stamp and jumps like a deer. Lead changes? No thanks. To put it nicely, you don’t exactly “click,” and who could blame you?