I wanted to make toasted bread for breakfast, but there are only three slices left, so when I toast the second batch, only one toasted slot has bread in it. Why do people do this to me?
If your toaster won't allow you to reheat things by putting them on the top of the apparatus with an add-on module, it's time to buy another. This purchase will make you feel much better about energy waste.
Regarding the OCD problem, it's easier, you should have cut it in two to use the two slots. That's why a 3-slot machine would have made things worse, if you wanted 2 or 4 slices, which I suppose are also likely choices some mornings.