It should work on anyone who hasn't been programmed by the watch. When they used it on Hayley before they weren't aware of the situation with Zenon. Perhaps this is less about it working and more about how to use it to deprogram Zenon's patients. On the other hand, Hayley hasn't been standing at Amy's desk demanding to see Zenon, so she probably wouldn't be the best guinea pig for that.
What was her programming, though? Amy was programmed by Zenon and then controlled via her trigger word by Derek, but what was Zenon doing with only one appointment with Haley? Or had he confirmed that she didn't have the watch from the get go so left her alone?
