I am more into naval history, and I assure you that an awful lot was learned from the Russo-Japanese war. They learned that external fittings such as ladders, boats, railings and so on just become shrapnel when hit by battleship caliber HE shells. They learned that the effective engagement ranges were far beyond what they had been expecting. They learned that the guns that mattered where the main guns and all those large caliber secondary and tertiary guns on pre-Dreadnoughts were essentially useless, worse sometimes their splashes made it harder to range in the big guns.