There are two distinct types of sautillé action. One uses the hand and one the forearm.
A common problem with the forearm action is that there is not enough flexibility and 'give' in the fingers and thumb of the bow hand.
Practicing an exaggerated bow change action in the stroke can help develop this 'give'.
As well as developing the finger movement, this is a good practice technique to learn to move from détaché to sautillé and vice versa....
