Len:
You questioned why are we making something so simple so complex? Bill gave an excellent response but let me add to it.
1) Because we want to, we enjoy it, and we learn from it

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2) Because while striking is simple it is complex.
Point two requires some explanation. Once you "get" a striking method then, with practice, striking can be simple.
However, since many people strike poorly, it REALLY isn't that simple. In addition, as Bill pointed out, in striking there is layer upon layer of how to strike harder. It just depends on how hard you what to hit or feel you need to hit.
Van often possess questions like: "Do you hit hard enough to stop the coked up 300 pound monster charging at you?" These are the questions that cause me to continually try to hit harder.
My question addressed a specific point and took it at a particular level. I knew it would draw out many and varied responses for me to ponder and learn from and it certainly did. All posts have been appreciated.
On striking I agree completely with Van (and everyone else) that you must strike through your target. I also agree that to teach that penetration, and the delivery of mass, that "time on target" is an excellent tool.
However, what I was questioning was that, once you have learned to hit with mass and to penetrate your target, do you need to:
"2. Hold the kick or punch at the extension for a split second so the movement will be complete."
In my opinion you do not. Once your shoken comes out their spine, either at the end of the reach of the strike or the end of how far it can penetrate that body mass, holding it for even a split second does NOT increase the force and (while a good training tool) eventually becomes an unnecessary step. Whether you go with my simplified physics equation that it may lessen the force, or with the statements made that it has no effect on the force, it still comes out as not being required.
So what?
Hey, no one need look any farther or any deeper into any subject than they want to, but I like peeling away all those layers. It is reported that Master Uechi used to say something like: In Uechi Ryu you never will see the bottom of the lake. It is just too deep. But I don't remember it going on to say "so don't look." So I look and look and look ....
I know you were just trying to ground things a bit, and no offence was taken, but the purpose of the thread was to go exactly where it went. Didn't predict the bikes though -- like em!
Rick