Tuckman's Stages of Team Development
Another wrong but useful model is the Tuckman's stages of group development.
This model articulates the four different stages that a team will encounter when starting to collaborate together.
Each time a member leaves a team, or each time a new member joins a team, it's not the previous team +1 or -1, it's a brand new team.
And this new team will go through the stages all over again: Forming, Storming, Norming, Performing to learn to collaborate efficiently.
Each member has to find their own place within the new group.
The group has to find its own way to operate.
This model can help to get prepared for the upcoming impacts when a team onboards a new teammate. It can also be used to trigger a change in the dynamic of a group. To help a team to change or re-invent their way to collaborate.
This model has been enriched later on with a last stage, the Adjourning stage which involves breaking or stopping the team.