I have flown at St. Auban France many times. They use lead and follow for instruction and as a way to check-out pilots before they let them fly cross-country on their own. The instructor flew a two place with a student and there were two or three single place planes.

We would all launch and gather at a staging area with well known lift. then the instructor would announce the next meeting area and off we all went following a course given by the instructor. We were always in direct vision with the others.

The system was very dependant upon the instructor pilot being an extreme master of soaring who would charge off to join up with a pilot in trouble and lead them to a thermal and gaggle with them during the climb. Some of the saves by the instructor were memorable. The instructor flew at least twice the milage of any other plane in the group.