If I remember right (and I may not be) in rotf they didn't have slot of time to film in Egypt yet that was a solid 1/2 he climax. How long is Chicago going to be?
This morning, Michael Bay tweeted that the climax will be "Long enough to be satisfying, but fast enough to leave us wanting more." No reports yet on how hard it will be, but it's Michael Bay, so I'm guessing pretty hard. You can trust me, I'm an insider.
It's a tough call. First film it worked out about right. Mission City didn't feel too long or too short. Egypt in Revenge of the Fallen seems to have lasted forever and got rather boring after a while. I think it depends on so many factors though it's hard guess before hand just how long the last battle in the third film should go on. If we get a lot of human extras and nameless protoforms fighting that could get boring fairly quickly. But if it's humans, Autobots, and Decepticons that have established a bit of character in the films it could keep a longer fight more interesting. I think Chicago also has the advantage of you can move the action over a street and change the background while the Egypt battle was just looking at a bunch of sand.
Whatever. I just want it to be GOOD. Have an actual fight this time maybe? All that matters is that you have fun right?
Action typically takes a lot longer to shoot than dialogue. Also, the vast majority of the "Egypt" scenes were shot in the U.S.
they need to have an epic huge battle like the forest fight megs vs prime in regards to intensity...then amp it up to the middle of a city with all the autobots and con's just knocking the hell out of each other for 1/2 the movie...and those standing win... simple enough.