You are probably the biggest Americana expert I know. I actually use this frequently and get commented that they rarely see people above white belts or heavy weights actively seeking this. All thanks to you btw.
That said, curious on your opinion on WHAT it actually attacks. This probably boils down to one’s own shoulder and elbow flexibility. But, do you feel that it would actually break the elbow (UCL?) more often than the rotator cuff?
I did some experiments and if applied where you pin the wrist, bring the elbow close to uke’s ribs, rev the autobike on both your wrists with both shoulders pinned - 2 ppl I tried it on all said they felt it on their elbow, 1 on shoulder. Now, when I did the Americana “wrongly” and had their elbow along the same dotted line of their shoulder and use my elbow to pull their elbow off the ground and PUSHED their wrist in an arc TOWARDS their body, 2 said they felt it in their shoulder, and 1 said they felt it along the line of their humerus. Is the americana actually more of a modified armlock rather than a shoulder lock?