I will chime in with several authors. First as background, I have flown lead, I have followed as a fledgling, and lead from behind. Now that I am instructing I prefer the last. As somone said, none of these techniques will make a cross country pilot out of one that is not ready or willing. But that said, part of the goal is to make fledgling pilots more comfortable away from home. Or for that matter, make the next airport feel like home (and the next, and the next...).

My experience following as a student, you don't learn much, as you just follow. As has been said, you must focus on following so not to lose the leader. For the most part, the decisions are the leaders.

Leading from behind puts the onus of keeping the formation in the hands of the more experienced pilot. Pick a "private" frequency and a lot of coaching can happen. When the student heads out, it is to the wide blue yonder, not on the heels of the instructor.

I have the privlage of a partnership in a duo, and have done a number of 2 place XC instructional flights in that. For students that are going to do there first XC in club ships (1-34 or B-4 in our case) the duo has an issue as the performance is perceived as vastly greater that the club ships. So, while we got them away from home, there is this lingering thought that "sure we went XC, but it was in a DUO". Not as effective as going in their own ship.

Now there is a place for all of this, but each has different benafits.

Rick