I believe the thing that many people struggle the most when it comes to improvisation is having to many wishes. Organ music is so wonderful and the repertoire is so vast, spanning almost seven centuries. Therefore, it is only natural that you like certain historical styles, composers, national schools of organ composition, or genres more than others.
If you do, then you might wish to learn to improvise like many various composers have done so in the past. In other words, you might want to imitate many different musical styles or genres. While this is a very positive sign in itself, I believe that at the beginning of your process in becoming a good improviser, having too many wishes can actually slow down your progress. I will explain why it is so in a moment.
Let's pretend you have a limited time during your day for improvisation practice. Let's say, you have 1 hour. You see, if you have only 60 minutes which you should spend on developing your improvisation skills, you should focus and practice in a way that allows you to progress the fastest.
If you love the music of 10 different organ composers and would like to imitate their styles in your improvisations, you only have 6 minutes for each of the composer, style, or genre. What can you achieve as an improviser in 6 minutes? Can you learn many interesting tricks or techniques that way? As a matter of fact, in 6 minutes, you will not be able to master even 1 sequence or a cadence.
By "master" I mean that you should be able to memorize it, and transpose it to 24 different keys at least 3 times in a row without mistakes. You will need much more time to do that. It will take at least 30 minutes or even longer, for most people.
And remember, that you have 9 other techniques, or tricks to learn and master. There is no way, you can do it in 1 hour. So I hope you see the inherent problem here.
In learning organ improvisation, you must learn to focus on the task at hand, finish it, and only then go on to the next task. If you like many different organ composers and genres, it is better to fully focus on only one or two techniques in one practice session.
In order to have the fastest progress in improvisation, the next day when you sit down on the organ bench, I recommend, you repeat the previously mastered material very briefly and only then learn something new.
Perhaps learning this way, you will learn to improvise only 1 piece or genre in a week or so but you will know that you gave your best focus. Even better, I suggest you choose one genre and work on it for a full month. We will call it "a genre of the month". Then the next month you go on to another technique or genre and practice it for a full month.
Use these tips in your practice to have the fastest progress in organ improvisation. This way you will overcome the biggest challenge of having too many wishes when learning to improvise.
By the way, do you want to learn to improvise in the style of Bach? If so, I suggest you check out my 9 day mini course in Keyboard Prelude Improvisation.
Or if you want to learn my special powerful techniques which help me to master any piece of organ music up to 10 times faster? If so, download my video Organ Practice Guide.