See link here: John Williams Hasn't Seen a Single Star Wars Movie
My iPad isn’t copying and pasting for some reason, but in the article, he says basically he only reviews scenes to add music but has never seen the movies end-to-end. Any of them.
Hilarious.
<shrug> I’ve heard many actors say they never watch their movies, too.
Williams is probably too busy.
No wonder his score was so bland and unforgettable.
I haven’t either. I tried a few times but do not care for the films. I find them corny at moments with what seems to me a rushed through plot. Star Trek has better pacing but I don’t like that show either. I didn’t like Battlestar Galactica but like those shiny robots.
Heretic! 
True story: the “Duel of the Fates” from episode one was so good as an apocalyptic theme that PBS’s Frontline used in the intro to their documentary about the Book of Revelation in the Bible instead of the overused O Fortuna (Carmina Burana).
The music for Episode I raised my expectation for the movie, but it turned out that the music was just about the only good thing.
As for the OP: I don’t see that to be so strange, by the time the recording of the movie is made the musical director would had seen virtually the whole movie many times over, so for him it is spoiled and even repeated.
Not much of an incentive to see it complete, and I do suspect that because of later editing some changes will end up being disliked by the score creators because then they needed to do extra recordings as a result, or their pieces are cut or truncated. In that case there is less of an incentive to see it. *
IMHO it would be like telling Leonardo that the feet of Christ in his Last Supper had to go because a new door was added to the wall, and he was told to paint around it.
Actors are often too self-conscious and only see the bad in their performance (in their view). This article reads like JW sees himself as a craftsman, plied his craft and moved on. Nothing wrong at all with it, but given the lofty praise with which his art his held, it’s kinda interesting.
I am not steeped in SW trivia but I get the feeling Harrison Ford feels the same way about his iconic roles. Showed up, hit my marks, did the scene - questions?
Useless bit of trivia! John Williams’ son, Joseph Williams, is the lead singer for my favorite band, Toto. Met him this summer and he seemed annoyed when anyone asked about his dad. 
Directors say the same, they see the film a gazillion times in the cutting room, and any further viewings after that are superfluous.
It’s a two hour film, and he’s had 40 years. I think he could find the time.
Bland and unforgettable? I can’t tell if this is a subtle point or just a snark fail.
Considering the movies contain some of the most famous music in movie history, you figure it out son. And not everything you don’t understand is necessarily a “fail.” It was just a joke.
Upon reading, you’re right it should’ve said “forgettable.” Snark fail.
Is this unique to Star Wars or does he generally not watch the movies he musics on?
According to what I just looked up, Williams is only 84.
I thought he was in his 80s 30 years ago.