Diabetes Q&A: 70/30; "Rule of Fifths"; Split-Mix; Basal-Bolus-- Which Is Best?

Q: During my training, most pediatric endocrinologists were using the "70/30 rule" or the "rule of fifths" to determine the insulin dosage for patients with new-onset diabetes. Now that I am in practice, I have heard that carbohydrate counting is a more accurate method of determining a child's insulin needs.

Is carbohydrate counting, in fact, a better approach to determining the insulin dosage for a patient with newly diagnosed diabetes? If so, how is this done for both regular and long-acting insulin? Do age and weight play a role?