To me milking is releasing as many games in a franchise as possible in a short period of time, for as many systems as possible, not trying at all to focus on quality.
Basically the stuff people love to throw around as being milked like COD, Assassins Creed, and Halo are not milked. They are highly successful, profitable, and get great critical acclaim. A better example is something like Guitar Hero which was releasing a new "game" every 3 months that was basically just a track pack and they were trying to sell it for full price.
Nothing wrong with releasing extra games on handhelds or other consoles, there is a demand for them, people want console franchises on their handheld, if there are 2 games released on home consoles and 2 games released on handhelds within the space of 4 years, I wouldn't say that the franchise has annual releases.