This is a workout that is done fairly frequently in order to work on speed. Normally we do not do this at scheduled team practice, but on easier days or when it is slightly too cold for intervals.
This workout began with 30 minutes of easy skiing. After this warm up we began to perform all out sprints. About every 3 minutes, the three of us would line up together, choose a start and finish line and race to it. We would then continue skiing until the next sprint. Sprints were around 15 seconds long and the presence of other people ensured that the speed was maximal. We then skied for another 30-40 minutes.
Using a loop trail with varied terrain is a good idea for this workout. In the Gatineau Park, you might consider a loop around Ridge Road trails 1-1B or 1-24 (both part of the Keskinada 50k skate) so you can work on technique at race speed on flats, dowhhills, and uphills. Doing this workout on part of a course you'll be racing on will benefit you on race day!
The purpose of this workout is to work on speed. As a result, the sprints should be kept short enough that speed does not suffer. 15 seconds is a good length because it is just before the maximal speed becomes tiring. I personally like using this workout 1-2 times/week starting in June or July, with it being done on most days in the 2 weeks leading into major competitions. This workout is not particularly fatiguing and is similar in effect to a distance workout with the added advantage of working on speed. Doing this with others has the advantage of encouraging speed, though it can easily be performed alone. The attempt to beat each other forced us to ski faster and helped fulfill the goal of the workout. I would be careful to keep the sprints short in order to prevent this becoming an interval workout. I would also be careful to ski easily in between as the priority is on the speed of the sprints, not the difficulty of the workout.