I put my empties in the bin - but -
Why have competion guns got ejectors. You can use the ejectors and pick the empties up afterwards and put them in the bin.
Put the bins in front of the shooter - this helps, not to one side or the other.
If a semi spits shells the other side of the rope or other barrier they cannot be retrieved.
you ever shot sporting using a non ejector i did for 3 stands drove me nuts gave up and switched to the old faithful