My parents live in a fairly rural place. It's sufficiently far from shops that in general they avoid doing food shopping more than once a week. This necessitates certain food storage measures such as putting bread in the freezer so it keeps longer. Sometimes lunchtime would come around and all the bread would be frozen. No problem, just cut off some frozen slices (harder than slicing unfrozen bread but you do get very neat slices) and pop them in the toaster for a bit. Result - fresh, perfectly formed, defrosted and delightfully warm slices of sandwich bread. But there is a complication! A standard toaster only takes two slices at once and (as you will know if you know me well) I have 3 slices of bread for my lunchtime sandwiches. Now, if I use a naive toaster slot allocation algorithm and completely defrost 2 slices first, followed by the third on its own, I not only have wasted one slot-toasting worth of electricity, but I now have one slice that is significantly warmer than the other two (or vice-versa). The solution is to use three half-toastings, each with a different combination of slices. I got extremely good at judging just how long to leave the slices in the toaster for.
This post was inspired by an Eddie Izzard bit about toasters that Gennie and I watched recently.