I had a strange experience the other day when playing a piece on the organ.
By now I usually don't need to write a lot of fingering and pedaling. I do it in the most crucial places.
But this piece had all of the fingerings written in. I'm repeating it from my previous studies.
When I played very slowly, I could follow each and every finger. These were good choices. Really helped to achieve the desired articulation.
But then I wanted to speed up to check how I'm doing at the concert tempo.
That's when the problems started to appear. First, my eyes didn't move that fast from one finger to another. And pedaling choices were confusing at this speed.
Then I decided to step back a little and to play as if from the distance. To have a bird's eye view on the score.
I guess my eyes didn't have to be stuck on the fingering and pedaling. Now I could just make music and let my muscle memory do the work.
It's like driving a car. The slower the car goes, the closer we can look at the road. The faster the speed - the further you have to look and predict challenges the car may encounter.
Hope this helps you too.