I don't wait. BUT, I have waited for tv series to come out on dvd because I passionately hate getting into it and having to wait an entire week for the next episode. I do this as a matter of course now. If I see something good then I watch maybe two episodes, and if it is still good then I wait for the box set.
I really hope my readers don't wait because I'm not sure there is an end! If they keep buying them then I'll just keep writing them... I could end up with twenty books in the series.
I had planned to finish at book three, and it is true that my sales rose significantly when I released book three. But there was a clamour for more, and book four has just as many readers as three and no visible drop off in sales, so hopefully there aren't any people waiting for some finish line!