Bulletproof the back of your shoulder before you press.
Keep the upper arm parallel to the floor, move only at the shoulder.
Raising the elbow to shoulder height before rotating puts the cuff to work in the overhead position, the arm angle where throwing, pressing and pulling overhead actually happen. Rotating the forearm up and back against the band from this 90-degree position trains shoulder control at the range where it's most often lost. One side works at a time, which matters, because throwing and pressing asymmetries are exactly what this drill exposes and fixes.
The elbow-at-side version is the entry point and trains the cuff in a safe, low position. Lifting the elbow to shoulder height moves the work into the overhead-relevant range, which is more demanding and more specific to pressing and throwing. Earn the 90-degree version by owning the basic one first.
Fatigue, or too much band. The upper arm must stay parallel to the floor throughout, so support it mentally like it's resting on a shelf, lighten the tension, and stop the set once the elbow starts sinking.
It's one of the most specific cuff drills for them, since it strengthens the exact position a throwing arm passes through. Keep it light and controlled, it's preparation work, not a max-effort lift.
