This is a complex subject because people complain from both sides. If you announce a game way ahead of its release, people complain that they're waiting too long (see pretty much every Sony exclusive game announced at E3 2016). If you announce a game too close to its launch and too far from the last entry in a series, people start saying that the series is dead (see Fallout 4).
Do you prefer to wait a lot but at least know that a game is coming or to not be sure if a game is coming but not having to wait too much after its announcement?