I can't say I am really surprised at which fandoms have a problem with this. I, myself, am a rapid IY fan; however, I never posted a negative review demanding that the writer finish it right now. I don't think myself that special lol.
Truth be told, I believe IY, YGO, HP, and Naruto have some of the biggest children/teenager followings. These people do not have any idea how long it takes to come out with a chapter. Myself, if I am lucky. A 2000 page chapter will take me 3 or four days. My own chapters are anywhere from 4,000-6000 (These can take me anywhere from 5 to ten days). I write for quality, so it takes longer. The problem with teenager followings is that many teenagers do not realise that real life comes in play with these story. One might have a family. I, myself, have a two year old with a husband. We have one computer, and if he is home from work he gets it. I only write on the computer nothing else. Next year it will be worse. I will be going back to school. I doubt my fan fictions will go away; however, they will be put on the back burner.
I can understand that the longer it takes to produce a chapter, the author is at risk to losing some reason. As a reader myself, I could wait for monthes between chapters. Look at it this way. It could be that the longer the wait the more quality will be to the chapter.