Chris, The biologic half-life of cortef is 8-12 hours. That means that after 8-12 hours half of the cortef his body absorbed in the the morning or at night will have been broken down. I don't ever remember taking three hydrocortisone (cortef) doses as a child (from about six years and older). It was always before breakfast and at bedtime. If your son is not showing any symptoms of low cortisol and his levels are OK you shouldn't worry. Joan