Most skiers routinely do quite a bit of distance training. This training, long at easy intensity, can be mid distance recovery, or longer routine distance sessions. In my training program, hour-long easy recovery workouts are common, and sessions from two to three hours for endurance building are more or less routine. Still, one thing that I think is occasionally overlooked is the impact of very long distance - or "overdistance" - workouts.
What overdistance entails depends on the person. It could be anything from the first (of many) two hour workouts, or it could be an epic seven hour slog. The important this is that it's a workout done entirely at a very easy pace that pushes your body beyond its normal endurance limits, beyond routine distance training, into a state of depletion. The benefits are both mental and physiological. Those who know about such things tell me that depletion training, achieved through overdistance, helps the body to better metabolize fats during activity, and to access hidden reserves of glycogen. In addition, the practice pushing those tired legs through the last half hour without falling flat on your face comes in handy on that final Keski climb.
This is not a workout to be done close to races; the draining effect on the body is deeper, and can take longer to recover from, than that of a tough interval workout. Still, during a break in the middle of ski season, there's no better way to spend a day than trying to do a 90km circumnavigation of Gatineau Park...
As the anti-sprinter, this is clearly a workout that appeals to me. Still, it's something I haven't done that much in the past, but have ended up doing a lot this year, and I'm very happy with how I feel about these workouts so far. I find that these workouts often happen accidentally, when a route is unfamiliar, as the time when Tom and I agreed that our run would be "long, but not epic - maybe three or, tops, four hours" before embarking on a five-hour North Shore exploration. The most important thing is to be prepared. Bringing more food and liquid than you think you need is good. Caching some partway along the route is better. Overdressing is infinitely preferable to the alternative, given the amount of energy the body will waste in keeping warm if necessary.
Find some good friends, pick a good route, and go long and easy. If nothing else, the hot shower at the end will make it seem all worth it.