The uk also did it for real at Taranto in 1940. So there were lots of examples to draw from. Perhaps the magnitude of success stemmed from the insight by genda and onishi to put the carriers together and train for mass attacks.
"The Royal Navy launched the first all-aircraft ship-to-ship naval attack in history, employing 21 Fairey Swordfish biplane torpedo bombers from the aircraft carrier HMS Illustrious in the Mediterranean Sea.
The attack struck the battle fleet of the Regia Marina at anchor in the harbour of Taranto, using aerial torpedoes despite the shallowness of the water. The success of this attack augured the ascendancy of naval aviation over the big guns of battleships. According to Admiral Cunningham, "Taranto, and the night of 11–12 November 1940, should be remembered forever as having shown once and for all that in the Fleet Air Arm the Navy has its most devastating weapon.""
Pretty much confirmed by my memory (my father-in-law was a retired Italian Navy Admiral, and knew war history very well), as well as by Wikipedia [0]:
"It is likely the Imperial Japanese Navy's staff carefully studied the Taranto raid during planning for the attack on Pearl Harbor, as both attacks faced similar issues attacking a shallow harbour"