the shorter the race, the less the scope for compensating for luck elements, which even out in longer races.
Quite often the "luck" mentioned in the assembly field will be the competitor getting away with a lack of concentration and/or some poor technical skills. But sometimes it will be a case of that micro route-choice really making a difference - taking a slightly different line of approach into an area is advantageous, getting the slightest glimpse of a control on a point feature in low-visibility forest, finding the "correct" thicket in a mass of thickets. There's sometimes a control which some people think is "bingo" yet others feel is fine. And so on...
So, how much of this is avoidable? Should luck play any role in orienteering?