Stability
Every team is like an organism that has unique traits. Also, like an organism they respond to stimuli around them. They also evolve to resist and overcome challenges.
Unlike organisms though, teams can alter their composition drastically and quickly.
Stability is Good
The concept of stability is a bit nuanced but in this case I want to frame stability as predictability. That is to say, given any kind of situation your team will respond predictably. This isn't always a desired response, but it is predictable.
Predictability is a wonderful trait to have as a leader as it means you can deduce what will likely happen without having to directly observe. It also is a strong signal that change is possible.
You need stability before introducing change. The reason for this is pretty simple—you need to see what impact it has. If you have a team that is unpredictable or unstable and try to make changes, you'll have a hard time knowing or inferring why things are happening the way they are.
The good news about stability is that all teams will create stability over time.
You can encourage this with intentional facilitation.
Change Makes Teams Unstable
The most obvious change teams experience is that people are added or removed. This creates a period of instability. Most folks only worry about the impact to productivity, but there is a lot more that can happen.
The introduction or removal of someone could have no obvious impact to productivity but begin to poison the team itself and over time this will appear as attrition and a crash of performance.
The adage goes that every time the folks on the team change, you have a new team emerge is true.
So what you need to do as a leader is be very careful about what changes you introduce, at what frequency, and what consequences you're paying attention to. Using 1-on-1 Meetings is a great way to detect what is happening. Building Self Managed Teams goes into developing signals that you can use to detect what else is going on. Finally, One Metric To Start, Get Started With Dev And Product Metrics and An Introduction to the Balanced Scorecard will help hone your sense of building out metrics.
How Quickly Do Teams Stabilize?
I generally see that most teams with involvement from an attentive leader or myself will show stability in about 3 months given significant change. That may sound like a long time, but compared to what I've observed it is much shorter than many teams that have no assistance.
This can be due to a number of factors like power dynamics, personality conflicts, expectation churn, and more.
As an example, I had to do a full transformation of a team in 3 months compared to the 8 it's sibling team. Both were given consultants to lead the effort, but one took 8-months, and mine took 3 and was considered more performant and more mature.