True, as I recall, Sauron was expecting, or so Gandalf speculated, that “one of the Captains of the West” would be showing up with the ring to challenge him.
I personally thought they did a remarkable job with the trilogy, in making it into a movie. My greatest lament, was that they cut out the confrontation between Sauraman and the company, after his defeat and the drowning of Isengaurd. Many important things were said and done during that meeting.
Gandalf tried to turn Sauraman back to the “cause” and finally had to break his staff. That was a significant event. I also was sorry that the changed the scene / dialog at the gates of Mordor.