I prefer groups that are non hierarchical, in which there is solid understanding of the goals and objectives, and everyone is relatively self sufficient, but anyone is ready to assist in an emergency.
So do I...
But sometimes I will hike with a group that is just a disorganized collection of friends of friends. I'm in that group to have a good time with these people, might as well fall behind and chat with the slow goers. I don't make any fuzz about it, there is no clear hierarchical formal assigment or public announcement of the "tail man".
If there's any trouble it is either going to be the tail group or the tail group is going to catch up with whoever who's having the trouble. The fast goers will have no clue about what's going on (Why aren't they coming? Trouble or are they just late? Should I go back and check, wait here or proceed?). I'd much rather be where the action is.