I believe that a third strike was planned, and the targets were the oil tank and docks. Nagumo did not want to push his luck, since he tended to play it conservative. If he had launched the third strike he may have run into the Enterprise just arriving at Pearl.
Real question: when the second wave returned to the Jap carriers reporting that no American carriers were in Pearl Harbor during the attack, did Nagumo and Yamamoto and Fuchida each say to themselves,
“We have royally f***ed ourselves!!”
Wait - Yamamoto is alledged to have remarked about awaking a sleeping giant & filling it with a terrible resolve. Too bad we never got to interview him after the war.