Michael made other mistakes that his father never would have made. For example, in the penultimate boathouse scene in II, he gives the order that "I want it [Roth's airplane] met" before Rocco, Neri and Hagen. Vito always gave orders involving death and violence to only one person at a time, the better to prevent having a rat become a corroborating witness.
Michael's biggest shortcoming IMHO was the same as Santino's...
he could not control his temper. Obvciously he was better at it than Santino, but he was not above raising his voice, pounding tables, slapping his wife around, yelling at Tom about not giveing him straight answers anymore, yelling at Frankie about a shooting where his wife sleeps, being so vindictive to Kay about not seeing her children, to name a few. Vito never raised his voice, and never lost his cool. I think in III when Michael is advising Vincent about how Sonny's temper did him in he is also talking about himself and how his loss of cool has "clouded the judgment." This is not so much failure to take his father's advice but it is a character flaw. Come to think of it, all Vito's children had temper issues. Sonny for sure, Fredo could lose it, Connie was a basket case, and Michael as stated.
