We tend to cook in quantities where there are leftovers: it's not
really practical to cook exactly the right amount of food, and it's
much better to have a bit extra than not enough. Plus with several
people working from home we tend to go through a good amount of
leftovers for lunches. One thing I've discovered recently with
leftovers: thicker sauces and soups make surprisingly good spreads.
For example, I recently had tomato soup sandwiches:
While something watery or brothy will stay that way even when cooler,
most things thicken up in the fridge to where they'll spread well on
bread. And it's very tasty!
I still mostly eat any leftover soups and sauces reheated, but if I
want something more portable I've been pretty happy with this.