If a cat does not just throw up hairballs sometimes but pukes out the cat-food regularly, directly or soon after eating. Then it is too much. Often people think their cat is just eating too fast and throws up because of it. However this behavior can also point to liver insufficiency.
Sorry for off topic: If your cat pukes very often, please get her liver values checked.
How often is too often?
If a cat does not just throw up hairballs sometimes but pukes out the cat-food regularly, directly or soon after eating. Then it is too much. Often people think their cat is just eating too fast and throws up because of it. However this behavior can also point to liver insufficiency.