It seems like the importance of having Retrospectives in Agile teams has been covered, and more and more teams understand the reasons behind it and believe in them. But the more Retrospectives you've completed, the more difficult it becomes to keep teams engaged.
For this reason I feel it is important to start discussing the importance of using various Retrospective techniques. If you are still not sure, why it's NOT ok to use the same technique every time, keep reading.
Professional Scrum Master II