I've been making this for years and with mashed potatoes and corn it is my DD's favorite meal. You don't specify what type of crackers you use, but I use saltine crackers in mine and I don't refrigerate for that long, if at all. It still comes out great!
I make this often. I am making it tonight in fact. It is delicious, easy, economical and a real pleaser every time I serve it. I usually accompany it with mashed potatoes, green beans and a salad. It's an excellent and tasty recipe!