When it is very dark or there are no ground lifghts or stars visible, if you were in doubt whether you were in cloud (which would require engine anti-icing to be on), then you would occasionally illuminate landing lights, or the lower powered 'runway turn off' lights to see. A major factor in any light bulb failure is cold starts and stops, so it is not encouraged to use the highly expensive landing light bulbs frequently. In difficult highly busy areas, you do tend to use them to enhance visibility. One place that springs to mind in near Lahore- the few crossings between India and Pakistan gets overloaded in the middle of the night with the SE Asia traffic heading to Europe crossing the Europe traffic heading to SE Asia, and the need to be in contact with about 3 ATC organisations at the same time.