I disagree.Filler episodes is for dragging it to the traditional 16 episodes length.And by definition, there is…
I trust the writers and the director, they take oportunities in these "filler episodes" to build characters so you get to know them better and their intentions, so many little details that seem like nothing happened but might be important in the future. Just today, 2 new characters were added (jin choyeon's father and mudeok's friend, and if theories are right, she will be used by Jinmu, creating another subplot). There's nothing worst than plain characters, you have to get attached to them so when the action comes you suffer or be happy with them. Story can't progress if people is always fighting, training and changing souls.
Following that line, they could have done a two hours movie and the 18 episodes left are fillers, this format is made to give more details about the universe, add plots and characters building.
And a traditional 16 episodes lenght drama can be dragged a lot too...
Filler episodes are made on purpose, perfect time for characters development, new characters introduction, explanations, opening and closing sub-plots ... trust me, if all the episodes were full of action and with many things going on it would be a mess, because we wouldn't have time to process everything and appreciate character development, no pogress in storyline
Following that line, they could have done a two hours movie and the 18 episodes left are fillers, this format is made to give more details about the universe, add plots and characters building.
And a traditional 16 episodes lenght drama can be dragged a lot too...