It doesn't matter how much some people here try to ignore it, if an update takes 9+ months and is constantly postponed, you should become a bit skeptical. It is possible to discuss something like this without it being regarded as a condemnation of the developer.
Especially perfectionists can benefit greatly from a little more time pressure. Not everyone who is creative is necessarily good at project management. If people always pretend that there is no problem with 9+ months per update, there is no hope for improvement.
Experience and staff size also play a role on development time.
We can discuss what is the ideal time frame per release, but a few things to consider first.
Compromises would be a natural consequence, that means, rushed story, cut content with unsatisfying result, worse renders, worse animations, shorter chapters, small segments of chapters release with dead ends waiting for new updates to complete the chapters... In the end of the day, it would more likely turn the game into a pile of shit, and make the playtime not great.
Also, if you think about it, if it takes 9 months for a complete chapter, or if we get 9 small release pieces of the same chapter each month, we would get the exact same product. In one case scenario means wait for a finished flashed out product, the other means less waiting but riddled with bugs, dead ends, save corruption, not worth update content length, and also would be more likely to delay the development process further.
Anyhow, next topic. Size. Simply put, it won't be a small update. I believe it would be worth of 2.5 - 5 months of other creators that rush and release content without quality. Now when you add the quality into the mix, and the good writing, I am fine with the time frame personally.
Does X or Y developers deliver more in the same time frame? Sure. But their game is not this game.
Personal level. Artists, writers and people that like quality, simply put, will feel bad if they have to release something in a shit state. As flawed humans are, you get to understand that in the long term run, if the developer doesn't feel good about their baby, it's doomed.
It's not a company business, in fact it's not even a business model we have here. It's a person who is developing a game, which get funded by people who want to support said person to keep doing what he/she enjoys doing. Therefore, the perfectionism rhetoric couldn't be less meaningless. In business there are metrics to beat, profit to generate, except this is not business.