Broth, man. Really not worth it for home cooks. If you’re a restaurant, though, going through dozens of chicken carcasses every day or breaking down beef quarters, all of the broth components are right there. It’s nothing to keep a 20 gallon pot full of bones & veg trimmings simmering for days. Home-made broth is an extravagance of special-bought, unusual items; restaurant broth is garbage collection. Side note, you can add a couple packets of non-flavored gelatin to canned broth to get a much richer experience. Still, I always go out if I have a craving for broth-forward soup.
Sandwiches, too - just doesn’t make any sense for me to buy a whole head of lettuce so I can put one leaf on bread.