How actually useful can route-learners that for most of the year operate in darkness actually be?
Learning in the dark can give you a different appreciation of the route. During the day, you can drive a lot on sight but as you lose visibility, you tend to drive more from memory. I've heard many Drivers say how different that a route is at night. Not forgetting that many brake points or route markers can't be seen at night. At night you can brake on a specific shadow or curvature. Night driving can get kinda freaky.