Staff training consists, as far as possible, in practice rather than in theory. During the war, military trainees had to study the current battles, analyze the mistakes made, and even visit the front to accustom themselves to actual combat. All branches of the army, including medical personnel and quartermaster corps underwent this same training.

And adaptation: intervention in Spain, early troubles in the Winter War, etc, experience led to refinement of relevant structures and hardware, failure meant overhaul ASAP.

The winter of 1969 was an exceptionally bitter one in the Soviet Far East. When the first clashes with the Chinese took place on the river Ussuri…the pressure exerted by the enemy was borne by the KGB frontier troops. After the clash was over, the General Staff held a careful investigation into all the mistakes and oversights which had occurred. It was quickly discovered that several KGB soldiers had frozen to death in the snow, simply because they had never received elementary instruction in sleeping out in temperatures below zero.

This was alarming news. A commission from the General Staff immediately carried out experiments with three divisions, chosen at random, and came to a depressing conclusion. Wartime experience had been irrevocably lost and the modern Soviet soldier had not been taught how he could sleep in the snow.

[...]

The chiefs of staff of all divisions were immediately summoned to Moscow. They were given a day’s instruction in the technique of sleeping out in snow at freezing temperatures, using only a greatcoat. Then each of them was required to convince himself that this was possible, by sleeping in the snow for three nights. (It should be remembered that March in Solnechnogorsk, near Moscow, is a hard month, with snow on the ground and temperatures below zero.) Then the chiefs of staff returned to their divisions and immediately the entire Soviet Army was put to a very hard test….

Two years before this, following the shameful defeats in Sinai, when it had become clear how much Arab soldiers fear tanks and napalm, urgent orders had been issued, making it compulsory for all Soviet soldiers and officers, up to the rank of general, to jump through roaring flames, and to shelter in shallow pits as tanks clattered by just above their heads, or, if they could not find even this protection, to lie on the ground between the tracks of the roaring vehicles.

— Viktor Suvorov. Inside the Soviet Army

This went almost from the start to the end.

A fair share of our military are poor white rural kids who can’t believe how incredibly well the army food is having grown up on roadkill and sunny delite