A good way to test this and use it is when you get an event that affects the health of your villagers. Instead of waiting for one or two healers (make sure they get plenty of practice too though) you can speed up the process of healing by using the children.

Remember when you hear someone SNEEZING, that is alerting you to the fact that someone is ALREADY getting healing -- a doctor is already administering help ... but COUGHING on the other hand, is a call for help.