and to an extent they aren't even really doing it
its not like they where able to come up with a movie trilogy, they just had well written literature to make the movies off of
I think Die Hard has pulled off the quad very nicely and that is all 90's I believe...or was the first late 80's....whatever its all the same
and Star Wars I think did its second trilogy very well even though reviews where lackluster for the first and underratedly mediocre for the second, the first is clearly the worst of the 6, but if you break it down how many comic book movies has the first chapter in the story been the best? or sci-fi (Star Wars OT, Terminator, Alien, X-men, Batman, Superman, most would say Spider-man and LOTR I think most would say their second movies are all superior to the first)
and I think Attack of Clones suffered from huge Phantom Menace syndrome, I think it is better than Jedi (don't stone me!) I'm aware most don't agree, but it has one of the most interesting stand alone stories I think cause it is pretty much the underworld of the the Empire rose
and then Revenge of the Sith is the masterpiece
so i definately think you can throw the other star wars trilogy in there too