I'm an aspiring author. Though I am fairly certain of the answer to the question below, I figured I would make sure, or at least collect opinions, since I have not 'been there.'
My question is this: In the event that you are writing a series, is there a disadvantageous number of books you can publish in that series?
Some series are trilogies. Some contain seven books, some four, some five, and some just seem to go on with no end. Is there a disadvantageous number of books you can have in a series? And if so, why?
Thanks in advance.
P.S. I am aware that it can be a bad idea to write more books in a series simply because the first book was successful. This question is aimed more at planned series.