What is the word or name for perception of time passing faster on a second trip on a route?

Not a single word, but the phrase that seems to come up most consistently, is "The Well-Travelled Road Effect".

Here is an article describing it: https://en.wikipedia.org/wiki/Well_travelled_road_effect

Basically, the idea is that as you travel a road with greater familiarity, you zone out, or your mind is able to wander and not be so completely engaged on the details of the route. This gives you the perception that time has passed more quickly.

I have experienced this many times as an adult, when driving a particular route becomes second-nature, or so easily navigated that at times I become especially alert and say to myself "Where am I? I think I zoned out there for a while."

The reason we do not have this same perception as a child is that a child's awareness is more open to the newness of surroundings, even when those surroundings may not have changed much. So, on long car rides that we have taken many times, the kids will say "how much longer??" every time we go.