The last box unpacked often contains things that belong more to memory than to the room.

The box that stays sealed longest is usually the one with no obvious place to go. Its contents are not useful in the new room, and that is exactly why they are hard to deal with: photographs, letters, things kept because of who gave them. Deferring it is not laziness. It is a way of not deciding yet what the past is going to occupy in a life that has moved on.

When you get to that box, take it slowly and out of the way of the move. Keep less than you fear and more than you think is sensible, and give what you keep an actual place.