When you have a lot of releases and many cards in the same column inside a given release, it becomes harder to drag the cards the way you want. Arrows would work better, in my opinion, in that case.

I suggest that the comportment be similar to when you drag a card with the mouse, i.e.:

- when you move up/down, you move by one card up/down or to the previous/next release
- when you move left/right, you move one column to the left/right