As a "victim" the touchstone of 9/11 is hugely important. As the aggressor 9/11 is a complete operation and the next "big" operation is being planned and 9/11 is ignored. As such in the plans of Al Queda 9/11 has little to no relevance other than a "lessons learned".

Even then 9/11 for Al Queda was only about 75 percent successful. One of the four planes did not hit it's intended target. As such the relevance is how to be more successful in the future. So far as a domestic entity Al Queda has succeeded with a truck bomb and a jet liner.

I would propose that the time delay to the next big successful attack is partially caused by looking for a new vector to to create fear and terror. That is why we haven't been attacked yet.