For me, the flow of the story as it is now is pretty good. But I do think that this series' once-a-month update makes it feel like it's dragging.
There are some authors that dont have the right of ending their stories because of the contracts with their editors. Somtheir stories end up too long or they dont have the motivation to continue them. Something similar happened to Bleach, as far as i know the mangaka did not want tomcontinue it but they pressured him so the story turned out pretty boring.
So i am not sure if its 100% the authors problem or not. Also, the story became slower during the twins scenes, that made us think the story was starting to get to its end.
I agree with the general feeling, there was a time i was super excited to get updates drom this story, also from akatsuki no yona xD now i just want them to reach their end and i hope they both end properly.
I used to love this story sooo much, but now I can't enjoy it anymore. It's like the author doesn't want to end it, I dont know if her profit with SB is just so grand for her to make this so unecessary slow or what.