I liked the JJ/Seeklander interview. Rob Leatham has a ton of great advice, and I would love to train with him sometime. However I find his way of explaining things unnecessarily opaque.
I don't find it helpful to focus on trigger manipulation as the single most important aspect of the kind of shooting I train for. It is part of an integrated system, which includes:
Aiming: seeing the alignment and trajectory of the gun and the target
Stability: stabilizing the gun--grip, arms, body posture
Trigger press: rapidly firing the gun without disturbing the alignment. (This is very important, as the quote in my signature implies)
Timing: pressing the trigger at the right time in the recoil cycle
Recoil management: adjusting the recoil of the gun and orbit of the sights
Transitions and upper body movement: movement of the gun to the next target
Movement of the whole body
In training, I isolate parts of the system to identify weakness and improve.