Shall we begin with qualifications: I am discussing written art and film/TV. I am discussing mainstream that was not originally planned as it was executed.
Alright, this is what I mean: Dragging out a story for more than it is. If you planned the book to be a standalone and you write another three because money. If a single movie is made, executed wonderfully, and a second is released that is not as good. That strays from the original to the point of nearly-nonresemblance.
I get it, money. But, can we find that line? Do you really need to keep dragging everything out long after it was dead? By going back to something that was already perfect and dragging it out, all you really accomplish is to degrade the original work. Now, what if it was written solely for money? Well, that is a little different, isn’t it?
Now, what if it was written solely for money? Well, that is a little different, isn’t it? Maybe. At that point, it should have been written/designed for the possibility to, eventually, be expanded upon. The kicker with that thought is continuity. It needs to work with the story. Stories do have rules and, yes, any writer worth his salt knows that most rules can be broken. BUT IT STILL NEEDS TO MAKE SENSE! To just abandon a story line means that you need to have a replacement that is just as good or better, and in the case of movies, this includes the acting and dialog. That can be what pushes your work over the edge.
This is part of my dislike of self-published book series.