well.. if it counts down every hour, then next turn would be redundant and thus a bug..
16+ hour travel for priests and advies works the same way. It counts down every hour until it hits 1 hour left. When that happens, you will arrive at the next turn change. Until then, you will start accumulating hours in your time pool. This is done to keep things certain travel-related checks centralized into the regular turn scripts, and not duplicated into the hourly priest/advy scripts.
This is intentional behavior, and not a bug.
