Does anyone know why the trilogy was such a revered form in the publishing industry for a while? I have on my shelf at this very minute three books that share a common universe, yes, but have no other connection between them. Not one character, plot-line, or even planet do they have in common, and yet they were marketed as a trilogy with matching covers. Further, I've heard of several instances where an author was done with a certain storyline after only one or two books and was asked to see if they could pad it out to three. So what gives? Was there some market research that showed trilogies were the most advantageous size for sales purposes or something?
This post brought to you by a series that ENDED after the second book and yet limped along into a third.