Many times a unit ends a turn with movement points left. In other games, either you are asked at the end of the turn if you want to go back and use up the rest of their movement. Other games do the pre-determined movement first, but that is terrible too, because you cannot react to what happened on your opponent's turn, you have to wait for the ship to go completely the wrong way, then bring it back again.
So, it would be nice if the game prompted you to finish fleet movements before the end of the turn.