Training observations

[Tukhachevskii]

That's incredibly stupid ******.

You can play the veteran card as much as you want, this doesn't change the fact that it's excessively bloody to figure out everything new during a war only.

There wasn't enough theorizing prior to the First World War, and the Second World War showed the power of theorizing done well. Combat experience is no important ingredient; the combat experience was more often than not largely irrelevant to the new challenges, if not misleading.
The US Navy didn't figure out air-sea battles based on North Sea patrols of 1918, nor did the USMC figure out the need for forced landings based on its trench war experience. Guderian didn't figure out the employment of mechanised combined arms formations based on WWI barrages and infantry assaults. Bloch didn't serve ever, but still proved to be a better seer in regard to military affairs than generals and field marshals with decades worth of small wars on their resume.

Nobody ever said "Let's wait till WW3 before we make up our minds on how to deal with a nuclear battlefield" because that would be an extremely stupid and potentially fatal idea.

Cant believe nobody has quoted Clausewitz' observation on the importance of theory for critical thinking and as part of historical research into trends in warfare etc (don't have the quote handy unfortunately).