Toaster ovens save some time, taking less than 5 minutes to pre-heat, versus as much as 15 minutes with conventional ovens. Additionally, some models have a convection feature that cooks up to 30% faster than traditional ovens, and offer consistent results. As far as clean-up goes, toaster ovens have a smaller surface area to speed clean up, and some higher-end models even have a self-cleaning feature.
However, using toaster ovens is out of the question for cooking family-sized meals. But to quickly cook small meals or reheat leftovers, they allow you to spend less time cooking, and more time enjoying your meals.