Another "interview" with Lucas excerpt:
In the opening sequence of Return of the Jedi, we see an Imperial shuttle exiting from an ORDINARY Star Destroyer. Yet, Vader is in the shuttle. Hence, Vader was on the Star Destroyer before the shuttle departed. However, we learnt from The Empire Strikes Back that Vader has his own SUPER Star Destroyer (The Executor). Why wasn't Vader departing from Executor but from a regular smaller Star Destroyer instead ? Does not make sense to me.
George Lucas: Your ignorance of Star Wars is embarrassing. Vader can’t utilize The Executor in normal operations due to terrorist activity by the Rebel Alliance. The Empire uses The Executor as a decoy so that Vader will not be assassinated. Vader travels in many different star destroyers so that the Rebels can never know where he really is. I bet you feel pretty stupid for asking this question.
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Yeah, most people call their loyal fans stupid.
RaYzor