Simple point is: stories (especially incest themed) doesn't need to have lots of chapters. Actually, it would be perfect to have simply 4-5 chapters and then move on with a new story, because in incest fantasy the most exciting part by far is beginning , when we see breaking of taboo, characters doing "unthinkable and prohibited". Once sex between them is "normalized", it's time to shut down the story and begin new one. I think we all know as readers or viewers that we feel most excitement when seeing that first 3-4 sex scenes between mom/son, or father/daughter. 18 chapters are really too much. Pegasus (and other artists too) could have use his time and talent to give us new stories, new characters, new first time taboos.