Completely depends on the animal. Many herbivores eat nearly continuously but carnivorous animals with low metabolisms like deep sea fish or snakes may not eat for months at a time. As warm-blooded omnivores we tend to eat fairly frequently but we're still between those two poles.

In general it's less about frequency than about overall food intake. Carnivores by nature of the difficulty of catching prey are more feast or famine. But again, it all depends on the exact species in question.