One additional advantage of the shotgun style is that you are for sure getting rid of "X" number of duplicate chips. (You send 3 chips to each of 10 people) You are hoping to get at least a fair number of chips back that are not duplicates. This works better if you collect chips from all over. Big disadvantage of the shotgun may be additional postage costs. Of course with a round robin, if you don't take any chips you are still going to pay upwards of $5 postage.