I've noticed the same. One kind of meat/poultry will be on sale one week, something else the next. So I've been able to buy a ~4-week supply of the meat that's on sale and freeze the extras & that gets me to the next time it is on sale. One of my 4 local stores will have tubs of greek yogurt on sale every couple of weeks, so I keep a 2-week supply to make it to the next sale somewhere.