I totally get where you're coming from, and I felt the same way at first. However, it helps to remember this is a solo project. Before Chapter 4 was released for free on itch.io, the dev was only working on it part-time which is standard for most debut AVNs. Now that Chapter 4 is out, the timeline should settle into a more typical 6 - 8 month update cycle.
Now you can argue for games like Once in a Lifetime, which finished in under two years, but that's a rare exception. Early Patreon success let the dev go full-time with a strict 2-month schedule, which most solo devs with day jobs simply can't match.