9-12 months for bigger update is usually on par for game like this. Especially when the story is so far along and become more complicated.
Not that I agree that Nyx is doing this, but, I agree with you about Patreon. I think a lot of devs tend to take more time for each updates, since they realize that they will end up making more money for less work, and not enough people keep them accountable for doing this. They have no real deadlines (except the ones they impose on themselves), and can lie about the number of hours they put on their work.
At the end of the day, people could easily pledge for a couple of months and take a break if they think the content shouldn't take this long/cost this much, and pledge back when it come out. It's on them to decide what the game is worth to them, nobody is forcing them to pledge each month of the "off time".
At least, it's far from WVM level of milking patreon.