It is the group leaders decision ultimately. He is the leader, you follow his rules or you drop from the group. You should ask at the beginning if you are unclear, although he should have also told you ahead of time.
So, the group leader rules on every OR ride I have been on or heard about are as you describe. Everyone rides at their pace and we will see you at the next turn.
But that is not the norm, most of the rest of the world does the conga line thing. We are special.