"Directing work" I believe is more effective with a larger tribe - the chief's "Influence" is supposed to increase with the size of the tribe. A child chief is definitely more useful at the start, but no, magic food doesn't even cover an hour of normal-speed play for a starting tribe, and the loss of work-hours is just not worth it at that stage, in my humble opinion. Which contradicts a post I've made in the past on the subject, but whatever.