In fact, there are a lot of politics that dictate who's names get put into the credits and where. So, like the above example, you would more likely be put into a "Special Thanks" section near the end of the credits, rather than with the members of the team who served until the end of the project.
A professor in school used to frequently remind students that if you leave a studio before a project is finished, then it is considered a "kiss of death." This may not be as relevant today as in the past, as there are many more contract and short-term positions on a team and studios know that their employees may leave to other, more secure opportunities. It may still not be the best etiquette, so instead of having your name blacklisted you may just not get credited as highly on a project as you would have liked.
At the end of the day it's just a title and doesn't mean much to anyway as it does to your own personal satisfaction. There was an intern that I worked with at the beginning of my career who's name was removed altogether from the credits of a game because the team did not like him and he didn't speak up for himself because he was shy. He found out about it by buying his own personal copy of the game to finish at home and did not see his name anywhere. He was so infuriated that he sent his ex-lead a nasty email about how it was unfair and how wrong the lead was, etc. This may have ended up being a career-threatening move, although the said person has since been able to find work albeit probably not as easily as he might otherwise encountered. Therefore, it's not as big of a deal as people make it out to be. The reputation you leave imprinted on your colleagues' memories is far more important than where your name is positioned in the credits.
If you did happen to want your name in a good spot in the credits, the best strategy is to stay on until the credits assignments are being decided, which is usually a few months until the completion of production. If you are hired to help finish a project--at the end--then you should be a shoe-in. You should advertise yourself by the games you've shipped, which basically means games you've worked on that were publicly released. So, if you were only on a project for a 9 month contract and didn't end up staying until the exact end of the game, then you are fine counting this as a shipped title on your resume.
-Ken
