Why in the world would you have to "see how they fast".
Many people have issues come up during a fast and if it's not a minor fast will call a Rav to see what to do about breaking it. Why would an extra fast help at all?
One side of the family is great fasters, other side can’t fast for 10 seconds. So we want to see which side each child takes after. Plus it makes them less nervous when they see it’s not a big deal.
