Having large groups of athletes can make it hard to do certain types of workouts effectively. As the number of athletes goes up, there is generally less time spent actually working out and more time spent waiting your turn. As a coach I found interval training the most intricate to organize, especially if there were wide ranging physical abilities in the group.
This workout can be done with groups of 4 or more. Odd numbered athlete groups will require the coach to participate since teams of two skiers are required. It is best if the teams are of equal strength (pairing strongest skier with weakest skier).
One team member of every team must start sprinting after the start signal and count 20 double pole pushes. The skier stops and calls out his teammate's name. The teammate must then sprint all the way to the first team member and then count 20 double pole pushes past him. After this the procedure is the same for any given amount of time. For intermediate skiers on rolling terrain, 20 minutes seems to be an ideal duration. There is usually isn't a defined finish line and because no one travels the same distance in 20 pushes, no winners are usually declared as no one remembers how many times they sprinted.
This workout is very nice when you have rivalries between skiers. They organize themselves to ski against each other and everyone ends up sprinting their own little races inside the bigger one. Rollerski speed often adds a touch of suspense as strong skiers with slow rollerskis do not want to get passed. With very large groups double poling is easier and safer but any technique can be used with the proper terrain. The workout developps speed, efficient recovery, strenght, balance and most of all team cohesion. This is best done as part of a larger workout and can be used to travel to and from the location of another part of the workout.