Adjourning is one of the most important phases in team development. The hardest times that to adjourn from a team is when the team is working very well together. High-performance groups are very hard to leave; groups that also have the clearest established norms are also difficult to leave. Those are the groups that work well together and show results.
The groups that I had a very hard time leaving are groups that I get along with personally and professionally. Getting closure can help a team move on to work on other teams. For these reasons, it is essential to adjourn from groups at the end of a project.