Whatever activity you and your horse engage in, be it eventing through to showing your horse, you start at the start, and aim to progress in your chosen activity. Some horses show a real talent for the activity you do with them, and can progress very quickly up the ranks. Time is spent teaching yourself and your horse to improve and achieve more.
These are two of the three essential elements to continuing to progress and realise your goals. The third is the one that is often forgotten, or not even known. And that is your horses psychological development.
If he is gifted at what he does, he may well find that his abilities put him in situations that his emotional mind is not yet able to cope with. To avoid this, and help your horse be the best he can be, add sessions that develop the emotional mind.
Give him different experiences so he gets used to the many different things he may be exposed to. Use some competitions as emotional development training, teaching him how to manage himself and cope with whatever novel things are in the arena/course, without pressure to perform. Finally, take emotional learning experiences at a pace he is comfortable with, and he will be reliable and confident wherever you go.