Nearly Stable Teams
Long-lived teams with stable membership over a long duration are generally seen as desirable. But there are downsides, and therefore I argue that development teams should exchange some members every now and then, especially in a product company that does not think in projects.
Let’s ask some authorities on the subject.
* The Scrum Guide does not mention how long a team should exist. No help here.
* Reading about product ownership or user stories, we find the hidden requirement to keep your team largely constant. Empirically measuring past velocity and forecasting future velocity only makes sense when the team velocity is not influenced all the time by changing team size, or by people leaving and other people being onboarded.
* When reading about feature teams, you find that work should come to the teams, the teams should not be formed around the work. The team is the fixed part, work (and knowledge) come to them.
* The Agile Manifesto asks that people voluntarily form a team around a vision. There is a project thinking behind this and the notion that the team is stable until the project is done and the vision fulfilled. The principle is difficult to map to a company with several products in different stages of their lifecycles. Additionally, taken literally, people may leave the team when motivation wanes, and others who feel the urge to help the project along may ask to join the team.
* Tuckman’s team model tells us that re-forming leads to storming, meaning that awful touchy-feely conflict overhead waste of time as opposed to the performing stage.
I can see that there is merit in the principle of stable teams. When you start out in an organization where people are pulled off projects and reassigned almost arbitrarily by managers, juggling several competing assignments at once, it is probably very beneficial to demand that a person work on one project for an extended duration of time, such as several days in a row. The longer one works toward the same vision, the higher the potential for identification with it. A long-term perspective for the team is the foundation for long-term team goals like learning and sharing knowledge with each other, improving quality of the deliverable, raising craftsmanship, and investing in relations among the team members.
My observations convinced me that this ideal is not to be pursued for several reasons.
For one, there is diversity. Diversity is generally seen as capability-enhancing for a team. There is diversity in work style, team role, experience, culture, gender and so on, but also in duration of team membership. Newcomers to a team are able to question an established consensus in a way the others cannot.
Then there is the team silo and local optimization. The longer a team works on its own, the greater the risk of losing the big picture and focusing on the local situation. When people switch teams every few months, informal bonds remain in place and people find it easier to connect across team boundaries. This is a powerful countermeasure against local optimization.
A stable team might over-optimize and establish routines and experts for certain topics. The possibility and the reality of a slow team churn enforces a culture of knowledge sharing, because in that situation it is dangerous to have a single point of knowledge for anything.
Finally, there is real life. People take a year off to travel the world or to raise kids, people leave and people are hired, so there will always be a change of faces in all teams. The more a team is experienced in handling these situations, the quicker they will pass through the storming phase and hardly see the storming as any bother at all.
To sum up, from my observations the recommendation is to make sure that every team exchanges at least one member every few months. If it does not happen anyway through new hires and the like, there are violence-free ways to ask people to take on other roles and to shuffle the teams by a small degree.
Just avoid the extremes: Do not reassign people by the hour, and do not keep teams stable for years. A healthy dose of change makes a team more resilient.