@ganymede Not sure why you think I meant you. I wasn't thinking that.
Also, saying, "Bringing only four sandwiches and giving them only to the same four people every time is not cool," is not the same as telling you who you must give your sandwiches to. You can only bring as much as you can bring to the pot luck, nobody expects you to make it a hardship on yourself to bring something, nobody is saying your having only four sandwiches reflects badly on you.
@Devrex You're describing a situation where sandwich clubs are invisible and harmless. There are a lot of dishes at this potluck. At one where there are fewer dishes and a lot of sandwich club members it goes:
Abelard brings four sandwiches. He gives them to Brigid, Camille, Darius, and Euphonia.
Brigid brings three brownies. She gives them to Abelard, Camille, and Darius.
Camille brings a box of wine, and shares it between the lot, and still has one or two glasses for whoever pounces at the right moment.
Darius brings five sandwiches and gives them to A, B, C and E, and sometimes gives out the fifth but just as often wraps it up and goes home for a nap. Euphonia brings chocolate-covered strawberries and hand-feeds 'em to Brigid.
Zane brought a big bowl of potato salad that's pretty good, but most people are full up on brownies and sandwiches and don't want any. Zane sucks the dregs out of the wine box and staggers around hoping Darius is gonna hand out that fifth sandwich this month. Yvonne, Xavier, Wendell, and Violet turn up, but individually, and each decides that a slosh of wine and a giant serving of potato salad do not a potluck make and leave, wondering why Zane is there and why Abelard and Brigid posted ads for the place.