If you go back and read about the Original trilogy in development it was just as made up as it went along as the sequels, George changed his plans a ton of times about very big factors while each of those films was being developed.
I am aware of the many changes that Lucas made while making the OT. However, he still had a general plan/outline for the story. Things like Anakin becoming Vader, Leia being Luke's sister, the other hope Yoda mentions in ESB, Wookies meant to be on Endor instead of Ewoks, all the changes he made, but he still had an outline. When he made the Prequels, he had it locked down, which is why they work so well as a story. I am glad that the Prequel haters finally get to see how bad Star Wars can be with the Sequal trilogy and are giving the Prequels their props now.
I honestly think it was more of a problem with Disney not planning rise of Skywalker well enough and trying to force way too much into that last film.
Any planning on Disney's part really. They literally released TFA with no idea how to follow it up or where the story would go. Disney planned on making money, and that was about it. In the process they tarnished the entire franchise and if not for all the Disney+ series being done by two actual fans, we would all be lamenting Lucas selling to Disney right now.
Force Awakens has a ton of potential, Last Jedi does a wonderful job of playing with that potential and taking it in lots of great unexpected directions, then Rise just tries to do too much in one film and doesn't manage to be satisfying because of that.
I kind of disagree on that point. I fully believe that Last Jedi wrecks the entire sequel trilogy. The only thing it gives us is another epic Super Dreadnought, a hyperspace ram, and pointlessly kills off yet another legacy character. It freaking ruins and wastes Luke Skywalker. It was so bad that Mark Hammil got in trouble for trying to warn fans before the film dropped.
The Force Awakens had some potential coming out of it, but honestly, Last Jedi did nothing with it. Po actually takes out a fleet killer dreadnought and is punished for it since they lost their bomber squadron in the process. Their base is destroyed and 90% of our heroes are on this slow death march until they run out of fuel the entire film. They pointlessly bicker among themselves, and even mutiny after Ackbar is ceremonilessly killed off. At this point we don't have anything for our heroes to do, so we sneak half of them off to get help disabling the Macgufifn. This of course achieves nothing. Then when they get to the planned destination, it's a last stand, and Luke shows up via Force Zoom call, resulting in his death. This major legacy death gives them about 5 extra minutes to evacuate everyone that is left into one single ship.
-ZacWilliam, if Rise had been two films, the first about the rumors of the Emporer tracking down the map and dealing with Kylo, and the second one had been about the final conflict with the New Sith and the diad, maybe a stormtrooper rebellion... I think both would have been greatly improved and had room to be better films.
See that, take those two films and replace TLJ and ROS with it, and you already put more thought into it than Disney ever did.
Like I said, there never was a plan and Johnson had no idea where to go with this film and tried to make it about character conflict instead of the actual galactic scale conflict the setting takes place in. How it got green lit is the biggest question I have. It should have never made it past the script stage.