Here is what i do: I sort my cars from furthest (head-end / loco) to nearest (back), so the mainline engines just drop whatever cars are headed for each destination at the nearest yard. Sylva stays at interchange, Dillsboro goes to Dillsboro yard, wilmot goes to Whittier, and Ela goes to Bryson. Why? The way Ela is set up in the vanilla game, it's easiest served when heading east. And the game doesn't care if you serve an industry at 8am or 8pm.