I remember a story I heard about how Richard Marquand wanted the duel in RotJ to be bigger and more elaborate than the one in Empire, but George told him that wasn’t necessary. Ultimately, the actual sword swinging should be secondary to the character interaction.
I finally found that Richard Marquand quote I was thinking of.
"There was a feeling I had that I would like the (Jedi lightsaber duel between Luke and Vader) to be bigger than the fight in Empire. And then George said that it doesn’t have to be bigger, because basically it can’t be. George is very blunt. He said, ‘It’s just a couple of guys banging sticks against each other. Don’t worry about that. It is bigger because of what is going on in their heads. That is what makes it bigger.’
I don’t really know how to reconcile this with George’s “bigger is better” attitude by the time of RotS.
I would say the duel in ROTJ is “bigger” than the one in ESB - for some definition of “bigger” I guess. It’s “bigger” in the sense that it’s a bit more sophisticated, choreography-wise, since Luke is a more advanced lightsaber user than he was in ESB. There’s more going on - he’s now fighting his father while at the same time trying to save his father, while the Emperor manipulates them both. Whereas, in ESB Luke was basically just fighting a bad guy that murdered his father. There’s a lot more going on psychologically AND physically in the ROTJ battle.
The ROTS battle had the potential to be incredible. Two former-friends and brothers in arms fighting each other to the death. The drama practically writes itself. But somehow it STILL didn’t work, mainly because (A) Anakin and Obi-Wan never actually seemed like good friends, apart from the opening sequence in ROTS, and (B) the action was so over the top; suspension of disbelief is broken long before they start hopping on floating platforms above a pit of lava like Mario and Luigi. However, the ending sequence where Anakin is dismembered is very good, in isolation.
George’s “bigger is better” attitude is apparent throughout the Prequels, where we see these huge CGI land/space battles with countless spaceships and vehicles. I think he adopted this attitude when he realized that CGI enabled him to basically do whatever he wanted. Somehow he didn’t see any problem with this, nor did he seem to notice that CGI often looks worse than physical models if not used correctly. I think Lucas always prioritized his reputation and the reputation of Industrial Light & Magic as a visual F/X pioneer. He certainly earned that reputation with the Original trilogy in the 70s and 80s. And Phantom Menace was ground-breaking in terms of VFX in many ways as well. But I think by the time of ROTS, the VFX efforts were producing diminishing returns at the expense of the story and quality of the movies.