There was no plan for the original trilogy either.
No - but you didn't see see TESB ignore much of what happened in ANH either.
And with Lucas involved, there was someone there with a single vision of where to go.
TFA was problematic in that it was competent...but average and left too many questioned unanswered. What should have come across as plot hooks for the next story came across as plot holes. All it would have needed was a few extra scenes or lines where Rey used the Force, showing her as talented but untrained. Never mind it was almost a beat for beat reshoot of ANH.
TLJ was problematic in that it ignored or actively dismissed much of what TFA setup. Then it compounded that error by dismissing some of the existing rules of the universe. The Holdo manuever, for example, might have looked great but it was a move that simply should not work in universe. It also made the bad guys look stupid and part of any competently told story is to try and hide the idiot stick. Add in the poor script, the nonsensical chase scene, the ability to track through hyperspace that was both new, previously impossible and yet used in ANH and TFA and TESB and elsewhere, the Canto Bight filler arc, the ridiculous mutiny and the fact Poe Dameron was a traitor who single handled wiped out the Resistance and there is much to dislike. I liked that RJ treid to introduce some grey into the universe, I liked DJ and his message, and I think Hamill did much to redeem the film. I think both Driver and Boyega showed huge improvement over their TFA roles. But overall, I think this film is easily the worst in the entire nonology. I appreciate not everyone feels that way but as I said, a few good moments doesn't make up for the Canto Bight scenes, doesn't make up for the Hoth rethread, doesn't make up for that silly chase sequence. And while both Driver and Boyega showed improvement, Isaac and Ridley - not so much. Course, it's kinda difficult to tell with Isaac as he didn't have much to do in TFA but Ridley was problematic because she was the central figure of the entire trilogy. She improved a bit for RoS but that isn't relevant for TLJ.
TLJ - I kept getting the feeling that there was entire subplots cut out. Poes unreasonable distrust of Holdo makes much more sense if there had been a traitor storyline. That the fleet was being tracked because of the traitor. That they couldn't jump because the traitor was simply hyperwvae the new lcoation. That Poe saw Holdo as the traitor. Isnetda they went with the lthe "Lets forget hyperspace tracking has been used before and then jump to the conclusion that the First Order found the fleet because it is now able to do what is now imposisble but isn't."
RoS had issues with its own set of impossibilities. Light speed skipping, another instance of the Holdo manuever, "retconning" Poes backstory, the sudden emergence of Palpatine and more. There is plenty to nit pick. And yet, the script is still tighter and more coherent and while it isn't perfect, it does an adequate job of picking up the threads left by TFA and TLJ and trying to weave them into a coherent whole. It could easily have been better...and yet, IMO, it is still, by far, the best of the sequel trilogy. There is plenty of stuff in RoS that needed further development - including Lando and his daughter - but there wasn't really time.