I don't even start following them until I know that the series has ended. For me, trying to read a series of books a few months or a year apart ruins it. I can't remember enough of the previous books to keep my interest. So, I have to wait and read them all at once. The two things that irritate me the most are when the author doesn't identify a book as the beginning of a series and when they've seen some success with what they've done and decide to continue on with it after it was supposed to be over.