Addressing swap numbers

If you host a swap and it is 5-for-5, then it is okay if the final quantity comes out to be a multiple of 5. But let's say you have 8 people in the swap total. That means that you will have 40 items to swap out. You do not not want one of yours back. Some swaps do give one of yours back. I don't see why you would unless you are creating a final piece of art.

Person 1 - 2, 3, 4, 5,6
Person 2 - 1, 3, 4, 5, 6
Person 3 - 1,2, 4, 5, 6
Person 4- 1,2,3,5,6
Person 5 - 1,2,3,4,6

At this point, there are no more of 1,5,6
One more of 2, 3,4
Person 6 - 2, 3, 4, 7,8
Person 7 - , 8
person 8 - 7, 8

If I started switching around, then I would be short for person 7 and 8. It never turns out right unless I contribute. I also ask for extras so I can scan them later to the group site. I might be wrong and I don't get all the possibilities correct or someone does not send the right amount.