This bugtracker thread was resolved, but there wasn't any real explanation given.
http://bugs.battlemaster.org/view.php?id=6133
I have an advy on Dwilight. Sometimes when facing a trip of more than 16 hours, I get a message of "He'll arrive in x hours"; there is a countdown, and then at the end he is told he'll arrive at the next turn change.
Other times (such as yesterday), facing the same time distance of 22 hours but moving to a different region, I click the travel button and *poof!* he arrives immediately (I think adding 22 fatigue, not 16, but can't confirm)
What is the difference?
Sometimes when you do a long (>16 hour) travel there is a small chance that you will make it in exactly 16 hours. This uses up all your hours and the travel is instant, just like normal.
If this does not happen, then you instantly use all 16 hours, move 16 hours closer to your destination, and then get one hour closer to your destination every time you would normally have gained an hour in your time pool. When you are one hour away from your destination you will stop using hours, start gaining hours, but stay one hour away. At the next turn change you will arrive with whatever hours in your time pool that you had accumulated.
ah, ok, so this is just a random chance, and doesn't have anything to do with where you are traveling or other discernible differences?
sounds fine - might be a good idea to add a message to that affect, like when a noble finds an easier route and saves time, to explain to players what is happening.
thanks
The chances of having to switch to turn-based movement increase with the length of the route.