I pretty much do the same thing, floating along the line from front to back as needed during the day. "As needed" depends on the group: how many new backpackers? How many other leaders? How many in the group have done this trail before? How far are we spreading out along the trail? How well-marked is the trail, and how many intersections with other trails or unmarked side trails?

A "typical" trip might mean two or three of us leading 6 to 12 newbies on a beginner's backpacking trip, with teaching occurring at rest stops and at camp. A group that large will often spread out a quarter mile along a trail, as people stop to fiddle with packs and clothes, or to catch their breath. We make sure there's a leader at or near the front, in the rear (that person passes no one), and one of us floats along that long middle section, keeping track of everyone and helping out as needed. At least once an hour, we stop to get everyone bunched up again.

If it's me and two or three experienced close friends, we constantly change places during the day, just so no one gets stuck in one place all the time.