For me, this manga is not that very slow and that it doesn't really repeat the same problem over and over again. The character development was more likely planned, it wasn't really slow as each phase of the story was beneficial for the proceeding parts of the story. You can see that problems that were stated in the past was able to make what they are today. This manga doesn't really focus on SEX that much so I guess that is what others meant by SLOW. Because reading it, the development was only right.
Some Spoilers Ahead
Volume 1 was building up first their characters and was also to better understand the setting of the story. The intricacy regarding Kabuki and also how the characters are doing in the setting was carefully plotted on the first volume and if it wasn't for this, the rest of the volumes wouldn't have a reason to exist. It would totally be not exquisite to just start with the CLIMAX immediately.
Volume 2 for me gave the start of the rising action of the story, yes it took 6 chapters to start the rising action but because volume 1 has already settled every intricacy there is to the story, the rising action smoothly went through. Volume 2 also completed the first phase of character development as it was ended with explaining how the feelings of Gensuke came to existence. Volume 2 having able to go smoothly and also having the characters finish the first phase of their development, the proceeding volumes would be easier to take in specially that in the next volumes, the scenes and the plot is more intricate. If I were to compare Volumes 1 and 2 to the next volumes, it is that the first two volumes were kind light and easy to take to the heart, volume 3 would be intermediary to the proceeding volumes.
Volume 3 would probably be the volume that I think took the most time of the story, like it was only to start up their romantic development which would prepare the 4th volume of this story. But I would forgive the slowness of this volume as it will make you get used more to the setting of Kabuki. You'd see more character developments in some more areas in this particular volume. If it wasn't for this volume, the next volume's settings would probably be brushed of. Like Kabuki isn't even part of the story, but because volume 3 was there, you would definitely get into the setting of Kabuki and it will ready you to absorb the intricacies in the 5th volume.
Volume 4 isn't the start of the climax yet, rather it is the phase in between the Climax and the start of the Rising action. In this volume, somehow the reason I didn't give it a 10 out of 10 is that the previous volume and this volume are the parts where I agree that the development of the story has been slow. But overall, it was probably because this volume focused on the romantic development of the story, so I can forgive the slow movement of this part as the first 3 volumes wasn't that fluffy either, only ambiguous feelings and uncertain thoughts. But somehow, this went smoothly to enter the climax of the story.
Volume 5 to me is the climax it self as this is the part where all the character developments, the intricacies of the setting and the romantic development of the characters will take place. Volume 5 exquisitely presented all the necessities of the first 4 volumes. This volume showed more drama and YES, LIFE LESSONS which I really think is the best reason why this volume is the climax. You see how much Sougorou learned from his previous experiences and how he overcame the lack of sex appeal, this also makes a lot of realization the part of gensuke specially when he was having a breakdown, if you were to see, a lot of previous volume references were used in the process of going through the volume. Specially so how Sougorou went past his troubles utilizing his love for gensuke. This shows how feelings are important in portrayal of a character and how it will lead to success and that it proves how "Experience is the best teacher". Not only this, due to that, Gensuke realized tons of things specially how it is that no matter how great you are in your field, if you don't use your feelings, you won't be able to show conviction to what you are doing. Gensuke realized that after talking to his beloved Sougorou. The success of both the characters in this volume gave the fulfillment we want from the story, in which I could conclude the next volume would probably be the falling action of the story as the volume was ended with the romantic side of the story, but reading Natsume Isaku's story, the next volume may or may not be the end HAHA. She might just insert another character to somehow disturb the lovebirds. But in all honesty, I am contented enough with the character development and also the setting, and is hoping that the next volume would focus on finishing their romantic development. I do predict that there will be talk of paparazzi or repulsion from family (on the side of Gensuke that is as the volume was ended with them being seen by his brother, though I don't think he will be the one against it, but hopefull she won't do that HAHAHA)
~KajiKouXaito