I try to utlize all leftovers in one form or another... only on occasion leftovers go untouched and are discarded after a week. Left over steak (any cut of meat) always goes nice on top of a green salad. Then if I am making a stew or soup, left over meats, beans, veggies can go in there with no issues.
I make a tortilla soup using left over cornbread, beans, and chicken and even noted it in my recipe.
We make pretty good use of our leftovers... more so than what we did years ago!