What will happen when a team is either split or joined with another team? After reading about Tuckman's stages of group development, I understand that the new team will probably start at the beginning or go back a few stages depending on how much they know each other and how much they have worked together before.

My questions are:

• Has there has been done any research on why you should or should not join or merge teams in short time periods?
• By how much will the efficiency drop by on average?
• How long does it take on average to become as efficient as before?

EDIT: To read more about tuckman's stages of group development you can go to this site. There is also some books written but to get a quick introduction this would suffice.