Let’s say you have a loop route. In one direction it’s mostly gently, but consistently and perceptively, uphill with several big descents and in the other direction it’s mostly gently downhill with several big climbs. Which direction do you pick?
I tend to pick the generally downhill route. I’d rather get my climbs over quickly on steep hills than slog it out going slowly uphill over a long distance.
If I plan on running the route more than once I’ll alternate directions.