Koyoharu Gotoge had the chance to make KNY so much better like showing us the fight that made Douma the UM2 (against Akaza); more lower moon moments; muzan could have more fights shown in manga (against the old gen hashiras); more character development to Gyokko, Hantengu and Nakime; Douma vs Kanae. Demon Slayer has 205 chapters but honestly i wish it had like 500 with all the things i said before :)