I don't know where you're getting this "rushed production" narrative from. Not only is it untrue, it's a completely irrelevant factor as it relates to the final product. We aren't talking about a 9 month production here - we're talking 2.5-3 years. Ultimately, it doesn't matter - Crystal Skull was 19 years after Last Crusade, did that help Lucas crack a better story? Civil War was 2 years after Winter Soldier, and 1 year after Age of Ultron and is arguably Marvel's best film..
Second, Williams had just as much time to compose this score as he has for any previous Star Wars film. I believe he actually started scoring TLJ earlier than he did any of the other films, which means more time to smooth things over during the editing process. In the film, this score contained no noticeable "harsh" edits or borrowing from other films' tracks, which is something AOTC, ROTS and TFA all suffered from because the score hadn't been updated after the editing process.
As for TLJ's score, I actually felt better about it leaving the theatre than I did TFA's. I have grown to really appreciate TFA's score, but it'll take time before I soak in TLJ's. Give it a chance. It might be better than you originally thought.