Flexibility is essential.
Sorry, ER, for letting this fall below the line. I'm sorry I don't have more time to dedicate to a long discussion, but I wanted to hit on a couple of points.
I've not read Tuchman. A lapse I'll seek to remedy. But from your synopsis, the German Plan was too perfect. Any plan that does not allow for variation is doomed.
I tend to resort to Sun Tzu in these things. I'm still not sure what he'd think o' nukes, but the concept of constant deception is the warp of the tapestry of the cold war. Civil defence efforts, being public, would be a natural conduit for a feint...but at great cost. Nukes up'd the stakes to a level Sun Tzu could not concieve of.
Not to mention what Sun Tzu'd think of our current engagement.