There are multiple good reasons for trading in a game once you have had enough, but in the eyes of Avalanche Studios founder Christofer Sundberg, length is the determining factor -- titles "have been too short," he told Edge. "I mean when you can play a game through from 8 to 10 hours, I would return the game too, because there's no reason for players to play it again.
"If you're offering little variation, then there's no motivation for the player to keep that game --unless they want to have a nice bookshelf," Sundberg explained. "That's why we answered that with Just Cause. I go into game stores each week and I always go to the used game boxes -- I usually don’t find that many [copies of our game]."
I don't disagree, though I do believe it depends on the type of game in question and the player's habits. For me, it's quality, not necessarily length. Some of my most-played games aren't "long" at all and yet here I am, unable to part ways. This is the sort of topic I'd love to see actual statistics on. Generally speaking, why do you (or don't you) trade in your games?