It's about the speed really
We have to be smart about our piano practice
Basically training your motor neurons
and requires specific yet fluid hand adjustments
link the physical and musical experience
If you read it every time, you are missing the point
without standing or making the thumb vertical
What is it and how to avoid it
The question was about the Rachmaninoff concerto but can it be applied to anything?
if your finger stays tense your thumb is not standing well, same for fingers, if they are solid,...
Kind of a continuation of a previous answer on practice