Giving positive group and individual feedback is easy, as is self-congratulation and, in many cases, it is hoped, this will be an accurate reflection on actual performance. When it comes to developmental or difficult feedback, it is only natural to want to move on and not reflect on the negative or developmental points, or why a negotiation did not achieve its objectives. But this is a mistake. The best learning opportunities come from reflection on what could be done better, and this can beachieved without blame, threat or condemnation.
Everyone and every team will make mistakes and/or have areas where they could have improved. Clearly, if every reflection session concludes that an individual or team keeps making the same mistake, then thereis a case to change roles or consider alternative approaches.
About Dos and Don'ts of reflection, you can refer here:
https://offices.depaul.edu/human-resources/employee-relations/Documents/Self%20Assesement.pdf