I wish I had a really good answer vilasman1.
Yeah, I know the catering guidelines.
We always ignore those and very much over buy (maybe because we were both raised by parents who experienced the Depression, we are gun shy about not having enough food).
A few years ago had over for a simple BBQ my MIL, FIL, SIL, my brother and his wife, two elderly grandmas and an aunt.
None of whom were chow hounds.
Hamburgers, two per person, a couple of pounds of specialty hot dogs, a cut of beef sliced thin and marinated in teriyaki sauce, several pounds of fantastic salads from a really great German deli, and I forget what else.
A ton of food for that crowd.
We had it knocked, or so we thought.
Don't know what happened, but even the grandmas turned into that thin Japanese guy who always wins the hot dog eating contest at Nathan's in Coney Island every July 4th (where does he put the stuff?).
Instead of relaxing during the party, was cutting and (briefly) marinating more beef and cleaning out the freezer for more hamburgers and dogs.
Finally, and just before I believed they would all explode, they stopped.
After that day, they all went back to their normal eating habits.
I still cannot figure it out.