Here are a few things that will happen in 2 years for you if you practice this way:
1. You could provide music for liturgy (preludes, offertories, communion, postludes, and interludes) on the fly.
2. You would have no fear of playing without a score in front of others, even the most experienced experts.
3. No more short breath, butter fingers, and performance anxiety.
4. More confidence in your skills.
5. More musicality when you play.
6. The excitement of risk of not knowing what you will create at the moment will become your friend, not enemy.
7. You will feel much freer with the music of others.
8. Better feel of the composition.
9. No more mechanical playing.
10. You will accomplish things faster in practice sessions on the organ.
If you knew all these benefits, would 10 minutes a day of improvisation practice (no matter how simple and naive at the beginning) would be worth to you?
[Thanks to Ed for inspiration]