Sorry GAW, but leaving a toaster oven on for extended periods seems risky. Even if you use a timer for say 2 hour periods, I’d be wary. If you don’t have an oven Yom Tov, you can cook instead. Not the same but better to be safe.
Have done it often, but agree that it is better to be safe. Some counter top ovens are made for continual use, others aren’t (and are made with automatic shut-off features). And check your smoke detectors!!