I don’t think SPAM is all that cheap. For the price of 3 cans, I can buy a large chicken and a bag of potatoes and have roast chicken, taters, gravy and sides/vegs on Sunday, for 4 of us. Then during the week we’ll have hot roast chicken sandwiches, a casserole or fricassee or tetrazzini, a soup or pot pie or dumplings, enchiladas or chicken spaghetti, with whatever staples that are on hand. And all those include leftovers that are taken to work for lunch.
Once when our son was little and things were tight, someone gave us a turkey and I managed to make it last 8 days (until payday), with a different, good meal every night.
There is no way that one chicken would last that long with 4 people eating. A meal, then hot sandwiches, then a casserole? You have GOT to be kidding—from one chicken. Must have been fed growth hormones to make it the size of a turkey!