This is a defining an issue which is not too much discussed in the classes of heli skiing technique. The visibility is linked to weather conditions and has a great influence on our way to ski. Understandably, as in any other form of "circulation", the heli skier must adapt their speed to the prevailing visibility conditions.
With a clear cloudless day, we tend to ski faster, because we see a larger open field in front of us, especially if no other skiers or obstacles are on the track. These also influence our visibility.