Yesterday when I was preheating my pizza stone for the requisite one hour, I baked a quiche. It's something I do a lot especially in the winter, multitasking my oven for multiple baking projects.
The hour-long pizza stone preheating time drove me crazy at first, especially because at 450 degrees, it makes for a very hot kitchen to boot. Then I realized I could actually take advantage of that hour, to roast beets (40 minutes), garlic (ditto), or potatoes. I dial down the temperature to the actual temp the things should bake and turn it up to 450 for the balance.
The other day I baked zucchini bread while baking a tofurky because both took over an hour to bake. Yeah for efficiency and economizing!