First of all, I give constitutional formulas (triunes ) for 4-6 month, not weeks. I also have patients check in every 2- 4 weeks to see if there are any problems, or need for re-evaluation. Most TCM practitioners are using acupuncture, which is done either weekly or multiple times per week and they often see acute cases, so more frequent changes in herbs may be appropriate. In practice most TCM herbalists I know do not change formulas every 10-14 days, more like a month or two at a minimum