Team members today barely have time to complete their work, let alone spend extra time on things such as defining a group process. This makes it even more important for individual contributors to know how to participate fully on a team right from the start.
Whether teams are officially put in place or not, groups will form. It is human nature. It is better for the manager, department, or company to control the forming of groups (by establishing teams) and to provide a clear purpose and focus for each group.