The "Don't arrive this turn" button is very helpful with that. Given that, *no one* should ever mess up a two-turn move. And probably not a three-turn move, either. When you get longer than that, all bets are off. The varied hours people get, plus the travel bonuses and delays, throw off most efforts at detailed planning.
You'd think so, but you can say, "Arrive at dawn," you can underline it, put it in italics, and repeat it again for good measure (I did all three in the same letter), and people still mess it up. It's like herding cats.