Team norms exist, whether you like it or not. Any team that works together develops a certain set of norms over time.
These organically developed norms, which are often unspoken, help team members know how to behave and interact with one another. While some norms help the team function more effectively, other norms might erode the team’s effectiveness.
One norm (which I liked) from several teams I worked with gives team members the freedom to voice out differing opinion, even if those opinions are contrary to the team leader’s opinion. One norm I often observe (and don’t like) is that of keeping quiet during meetings because “it’s not going to make any difference!”
As a team leader, if I could have a set of constructive team norms that help my team work more effectively together, and not have any norms that might negatively impact the team, I would have a better team. I would then have more time to lead and empower the team and spend less time dealing with misunderstandings and mismatch of expectations.