I recently competed in a local 5km Running Race in which I have competed for the last 3 summers. I attempted to run with the two leaders and after 2km I was unable to hold their pace, finishing in a time 40 seconds slower than last year when I didn't attempt to run with the leaders. One of the people who passed me late in the race, commented on my fade and I realised that I was not that disappointed. I knew it was possible to run with them, I tried, and they were faster than me. I was pleased that I had raced to win and raced at my limits rather than being cautious.
Racing is about competition and attempting to win. Races are not won (I am thinking of mass-start events here) by allowing others to go ahead and sticking to your own pace. Winning, (and unexpectedly good performances) occurs after taking risks and attempting to ski with faster skiers despite the risk of failure. An aggressive attitude to racing will sometimes fail but it will also tend to yield better results than caution.
In the Olympic 50km in 1998, Christian Hoffman started at a pace that few expected him to maintain and he led for the first 35km. He faded but despite the fade managed an Olympic Bronze Medal. Had he raced at a more cautious pace which he would have expected to hold, he would not likely have medaled. The risks he took in pacing produced a very successful and unexpected result. Bjorn Dahlie had a reputation for racing this way as well.
Limits are never learned without hitting them. By not racing aggressively, we never learn what is possible and improvement is more difficult. A pace that is cautiously measured to ensure it can be maintained will not often produce an all-out effort and therefore not produce the best possible time. Aggressive pacing is also useful in individual start races as it allows us to approach our limits and provides for unexpected possibilities.
Despite the benefits to aggressive racing and taking there are some benefits to a certain degree of pacing. One must start races at a pace that can possibly be held. When I faded at that recent 5km, I started at a pace that was not unrealistic. I couldn't hold it that day in those conditions but it is a pace I am likely capable of running. Likewise, in that Olympic 50km, Hoffman started at a fast pace but one which was capable of being maintained by the best skiers. He was aggressive, but not completely unrealistic.
To make a long story short, the point being made is this: It is worthwhile to take strategic risks and to strive for the absolute limits of one's ability, even if the strategy backfires from time to time. Give it a try at your next local race or timetrial!