Using pharmacokinetics integrated with in vitro data, the authors are attempting to define the best dose for HCQ both for treatment and for clinical trials, while avoiding the heart QT problem of higher doses.
Notice that in the chart, the higher dose and the 10-day periods resulted in the lowest viral load compared to the lower dose and shorter treatment period. The addition of azithromycin antibiotic also appeared to be better than the HCQ alone, although since those groups got it three times a day (TID) and not twice a day (BID) it is hard to compare. The amount of zinc consumed doesn’t appear to be included, at least not in this chart.
The least viral load after treatment appears to be 600 mg HCQ twice a day for 10 days, but even 200 mg HCQ twice a day for 5 days is better than nothing (the black column on the left). Keep that in mind when you read other studies.