This starts even in Basic training, where we were trained by our Drill Sergeants on how to establish a base perimeter and command what troops were left.
We were also trained to realize that even as a junior enlisted man, the lives of hundreds of fellow troops relied on how well you performed. My ARMY Drill Sergeant told us the story of Doug Hegdahl, a teenaged NAVY sailor blown off the deck of a ship and captured by the North Vietnamese. Because of his resourcefulness, he possibly saved the lives of hundreds of his fellow POW's.
This reminded us to take our training very seriously.
That’s all fine, but the point is that in a multi-year peer war, after year one, NCOs with “years of training” will all be gone, and the NCOs who take over will have weeks or months of training.
If your basic force structure relies on NCOs with “years of training” and you don’t have any, you have to change your basic defence strategy in the middle of a war, on the fly.
Better to be realistic and set things up before hand.