d-ac-space-around to pack rows along the element's cross axis so that there is an equal amount of space on each side of the item. This effectively takes all available space, divides it for each row, placing half of alotted space on either side of the row. This is why the space appears doubled for interior rows versus end rows.
d-ac-space-evenly to distribute rows along the element's cross axis so that there is an equal amount of space on each side of the rows, but unlike
d-ac-space-around the space visually looks evenly distributed between objects.