I actually use CT's squat from pins as an activation exercise. Today this is how I used it:
Set pins in power rack at so bar was at bottom of sternum, then the following weight progression:
Then did back squat and hit an all-time PR using following loading:
425x1 - loose belt
495 - walk out and hold for 3 secs
465x1 - loose belt and loose neoprene knee sleeves, went up pretty easily. I think it's because of using the top half squat from pins- Thibs has mentioned something about disinhibting the Golgi Tendon Organ reflex something or other. All I know is it's the most I've ever squated in my life and was pretty happy. The top half squat from pins has really helped me, thankful to CT for his advice.