He won two Oscars in this time (Best Supporting Actor for The Godfather Part II and Best Actor for Raging Bull) while four of those films were nominated for Best Picture and two of them won (The Godfather Part II and The Deer Hunter.)
Al Pacino in only three years put in stunning performances in The Godfather Part I and II, Dog Day Afternoon and Serpico but criminally didn't win a single Oscar.
Who are some other actors who had periods where they were in consistently great films?