MMOs are big. Really big. You wouldn’t believe just how mind-bogglingly big they really are. Although you probably would, since you’re here reading about them. And the sheer facet of scale means that it can be really difficult to establish a point when you’ve seen enough to have a good sense of the game.
Obviously, five minutes logged into an official World of Warcraft server won’t give you any idea about the game as a whole; pretty much anyone could agree on that. And at the other extreme, it’s unlikely anyone would expect you to play every piece of content in Star Wars: The Old Republic before you can decide on whether or not the game delivers on what you’re looking for.
Realistically, every game offers you a different amount of things in different combinations and in such arrangements that every game will require different amounts of time to evaluate. You could argue that a few matches in World of Tanks tell the whole story about the game’s mechanics, after all. But then, just playing and leaving means you miss out on the meta and the overall sense of what the game is like over the longer term, which can often be a pretty important element. So what do you think, readers? How much of an MMO do you have to play before you feel you’ve got a handle on it?