The absence of control on the rebounce of hand - and arm - after the beat is one of the most frequent defects and difficult to eradicate.
My students very well know this problem.
The pattern of two in animated tempos is undoubtedly the most difficult, and the rebounce after second impulse potentially can create more problems.
The hand jumps up almost without control and this gesture even if it may seem imperceptible can provokes imbalances accelerations and rushing.
And unfortunately, alas, this problem affects all...
https://www.youtube.com/watch?v=WR_MJOwNbaQ
