I admit to being clueless into game planning except for we'll run  or pass more than usual. I'm guessing that if an opponent has a great passing attack but sucks on the run we spend some time tightening up our pass D or maybe add a wrinkle or two. Same with run ability. On offense the same. Figure out opponents strengths and weaknesses and then tweak plays to take advantage.

Beyond that what takes a week to prepare the plan for the next game? Especially because once the game starts the plan could easily be out the window and in game strategies adjusted to account for the unexpected.