Some very successful authors have difficulty in delivering books to wrap up the series. Why do you think this happens, and what is the best attitude and healthy behaviours die hard fans should use to encourage authors to deliver the books they are hanging out for?
Anytime you get into “should”, that is dangerous ground. I am a creator and I do not think I should be dictating fan behavior. That’s your world as a community to decide upon; I prefer to let the community do it's thing.
I do not think there is one good answer to this. (IE, why other authors are sometimes slow.) One common answer is that it has been a hard decade for a lot of people. Man, there are often difficult things about this last decade that have been draining to people. Then add on to that personal issues, and it is very hard for some of my colleagues to be creative in the way they have to be to write a novel.
Another big reason is that many authors tend to be “discovery writers.” Their biggest strength tends to lie in character interaction and believability in those characters. They give their characters so much volition. A discovery writer does not know their ending, they just start writing and let the characters interact. While those interactions often shine, the authors often have weaker endings. That is not to say that all discovery writers have bad endings, it just takes much more revision. It tends to be very daunting and slows them down towards the end. It is simply an outgrowth of their writing style.
Add on top of that expectations, and maybe never having finished something on this level before, and suddenly your stress is through the roof. These authors, I should remind, just started out like the rest of us. Unknown and just trying to tell a good story. To suddenly have the world watching can be extremely daunting, and there's really no way to practice for this. It can honestly be debilitating.
I think all the various fan reactions are understandable and in some ways they are necessary to the fandom’s psychology. I do not visit the places that exist to complain about me, to complain about my style and tropes. But those places existing is healthy. It is healthy to have a place to talk to people with similar opinions to you or to just post some memes and have some lols.
It can be unhealthy when it becomes harassing behavior. One thing I do not like is how our society treats people who like things. If you speak about liking something online, people will try to rip that away from you. This rubs me absolutely the wrong way. This isn't to say all criticism and disagreement should be done away with. I like is interesting conversations between people who disagree. I disagree wildly with Peter (this is Peter Ahlstrom, my VP of editorial at my company) about Into the Spiderverse. He could not stand it, while it is one of my favorite movies. (He didn't like the framerate of the animation; it drove him crazy.)
Fan criticism also becomes toxic when it becomes harassment to the creator. I do not know where these lines are, though. It's a tough one, because simply posting your opinion online shouldn't constitute harassment.
If you want my opinion, if an author says they are working on a book, they are. I know these people; they want to be done as much as you want them to be done. But there are mental, emotional, and sometimes physical difficulties preventing it. At this point, there really isn't much you can do. And I bet that the harassment of these creators has slowed the release of these books.