Then why didn't Mitt Romney know what to do when Candy Crowley propped up Barack Obama with the infamous "transcript" remark?
Just when you think you've got everything "gamed out," there's one more game, the one you didn't imagine. But even if you could know "every potential permutation" and you could figure out the ideal reaction to each one — which is obviously impossible — could you memorize all those things and in the heat of the moment call to mind the correct one each time and deploy it? Wouldn't you look weirdly robotic cranking through all the alternatives? It's hard enough to read a prepared speech off the teleprompter in a naturally human way. And there's already a meme that Hillary is a robot. More here.
The ideal response would have to take into account how the people respond on an emotional level. There's no perfect scripted zinger for that. There's no planned facial expression or hand gesture. We the People are very sensitive to what we see and hear. We feel that we feel whether a person is good and true. We are manipulable and we can be faked out, but I think we are more likely to be manipulated and faked out by Trump's I'm-being-myself approach than by Hillary's gigantic team gaming out every potential permutation of what might happen.