So, what is the fastest way to achieve that level of competence? The answer to this is simple: slow, regular, and persistent practice.
By slow, I mean we should practice pieces in a slow tempo. Even the fast tempo pieces should be practiced this way. The tempo will become easy if you will know the piece very well. There are various practice techniques that help achieve fast tempo but generally speaking, we have to take such practice tempo in which we would avoid making mistakes.
In addition, we have to practice regularly. By regular practice, I mean that ideally we should practice every day. It does not always have to be two or more hours of practice, but try not to skip practicing. Even if you have only 20 minutes available, repeat the work that you practiced the day before and it will become a little better every time you practice it.
There is a saying among organists, that if we skip one day without practice then only we notice it. If we don't practice for two days, then our friends will start noticing it. If we spend three days without practice, then everyone will notice it.
Finally, it is important that we have persistance in practice. For example, what do we do if we find a challenging spot in the music and we make mistakes? There are three options:
1) correct the mistakes
2) play with mistakes
3) choose another piece
Ideally, we should strive for option 1. And that often takes persistance. Very often we will get discouraged by the difficult places in a piece. We don't always see the solution very clearly. But if we have persistance, then we'll find the way out eventually. By the way, option 3 might be a good solution, if the piece is too difficult to play comparing with our current level of ability.
So the fastest way to achieve higher level in organ playing would require slow, regular, and persistent practice. I sure hope you are practicing this way.
By the way, do you want to learn to play the King of Instruments - the pipe organ? If so, download my FREE video guide: "How to Master Any Organ Composition" in which I will show you my EXACT steps, techniques, and methods that I use to practice, learn and master any piece of organ music.