I learned this drill from Kody Burns at Gripmas. He said he does this a lot with the Euro 1 Hand Pinch.
He said it’s More on One Hand Pinch Rotational Training
Technique is very important in producing big lifts and feats. It is equally as important as employing the right training methods.
The Finnish group of More on How to Pinch Plates
As I say in the video, there are several ways to get stronger: Lift more weight, Lift the same weight more times, etc.