Isn't the tactical playbook set On High? Obviously you need to react to a changing situation in combat, but wouldn't the standard responses to various situations be planned/tested/approved and then turned into training material by some central authority? Or is that sort of thing more up to officers in the field?
The Soviet military used that system, including algorithms to determine which tactical approach to apply. Western military's have long focused on small unit initiative and rewarding novel tactics. A wartime military is the ultimate meritocracy.
Even in WWI, which is often stereotyped as stupid generals sending men walking into machine gun fire, there was a huge amount of tactical innovation from the lower levels (by 1917 they had developed the small unit tactics we still use today).