In general, serious illnesses with strong symptoms are treated with large doses of carefully crafted formulae. This maximizes benefit and minimizes side-effects. If one is not doing precise bian zheng lun zhi, one should use smaller doses to avoid adverse effects. Treating chronic complaints is different. They generally involve varying combinations of excess and deficiency.
Many times there is a good base formula to treat the apparent root of the patient's constitution.
However, these formulas often do not address the complicated branches of most chronic disease. Sometimes there is a good branch formula available that can be combined with a root formula to treat a particular patient. In such cases, it is still common to make deletions and additions. Some formulas are designed to treat root and branch, excess and deficiency. In such cases, it is still common to make deletions and additions.