Shizune's route has three primary characters (Hisao, Shizune, Misha) and an assortment of secondary characters who, for the most part, get little more than cameos (Lilly, Akira, Hideaki, Jigoro, Aoi, Keiko, Kenji, Mutou, Yuuko, Nurse(?)). By comparison, Lilly's route has four primary characters (Hisao, Lilly, Akira, Hanako) and an assortment of secondary characters who, for the most part, get little more than cameos (Shizune, Misha, Hideaki, Rin, Emi, Othello, Kenji, Mutou, Yuuko, Nurse). That's right - Lilly's route has more characters, even when I cheat and give it the twofer of Aoi and Keiko.
>Lilly is pretty much the same person from beginning to end and the route addresses her own issues
This is the problem, especially when people criticize Shizune for the lack of character development. Lilly is too perfect to change, hopefully she doesn't hide another relationship destroying secret from him in the future.
People also shit on the route for only having one choice when really most other choices in the novel are either superfluous or illogical. In Lilly's route, there is no reason to lie in any of the choices presented especially when you're required to be honest to get into it in the first place. It's counter to the themes in which Hisao learns to stop relying on her... by continuing to rely on her.
>his heart condition in the forefront of the story
It was a plot device to get them together. Hisao is a dumbass but fucking forgetting 17 pills? He hasn't been excercising but suddenly he can run miles to Shizune's house and the airport but only collapse at the last minute? It's just lazy writing.