The Red Army he have seen emerged from several iterations of intense debugging. It was not just experience of WW I and Civil War, and then “let’s prepare for the last war”.

Not counting misadventures of Tukhachevsky in Poland… But in Spain, Winter War, Soviet-Japanese war? Early performance was scrutinized, and when anything wasn’t good enough, improvements in tactics, training, equipment and organization made ASAP. Testing new equipment in real conditions, too. In particular, several competing heavy tank prototypes were field-tested in Finland, air MRLS in Far East (as a fighter shock weapon, but this helped with ground attack planes later).

As to the equipment, part of the reason is that the top level specifications weren’t generated by committee, and proper feedback was enforced when possible. Stalin not only paid attention, he invited the lead military hardware designers for a personal audience, one by one. A CMM-5 grade process.