I'm training the rear delts in a reverse-benchpress movement. The problem is maintaining consistent elbow positioning. It is too easy to compensate for progressive overload by tucking the elbows closer to ones torso than one should. Eventually one ends up with a weight too heavy to do the exercise correctly. Progressive overload results only in the progressive lowering of the elbow instead of strength-progression. Like Athlean-X demonstrates here:
https://youtu.be/3eOFjmSM9s8?t=4m50s
How can I prevent this?