Kind unrelated, but Italy and Japanese has quite unique doctrine, one is restricted by mountains and resources, and the other is restricted by oceans and resources, tho in hindsight they should know they are already fighting in North Africa and northern Chinese plain. Even then by 1935 standard both of their tank force are roughly equivalent to other major powers, in the battle of Battles of Khalkhin Gol Japanese medium tanks are still evenly matched with Soviet T-26 and BT series in armor, just lack in fire power and number. But the thing is tank development takes on turbo mode after Spanish civil war, by 1940s you have monsters like KV-1, T-34 already in service, and those would be obsolete in just 2 to 3 years. Japanese, Italy and other minor powers like Romania, Hungary just don't have the industrial capacity to catch on.
For how far the tank design progress, US medium tank went from this to this in 1 year, the former is lighter than a light reconnaissance tank before end of the war
https://en.wikipedia.org/wiki/M2_medium_tank
https://en.wikipedia.org/wiki/M4_Sherman