So I buy version X, and unlike any other game genre, to get the latest version I have to pay a monthly fee to get it. That's your choice. You could put the update on Itch, where I have bought the game from at the same time as Patreon's. Everything devs do is their choice. There are games on Steam that have 2 chapters, on Patreon there are 9 chapters, and people on Steam have waited 6 months for these other 7 chapters. Be like most other games, release them at 1.0 (i.e. finished) and then charge more for them. Given VNs are so story based, it is so frustrating getting to an arbitrary end and not know when you are going to be able to continue with the story.
VNs are a tiny market because devs are more interested in Patreon's than customers, who bought their game on Itch or Steam!