Evolution of the binned RV variation, rms_RVb, owing to activity-related group spots (left panel) and to all kind of stellar noises (right panel) as a function of the binning in days. The three strategies shown for different (given for each lines) use three measurements per night of 10 min and 10 nights of observation per month. The only difference lies in the spacing between each night of observation. Thicks lines correspond to the 3N1 strategy, thin lines to the 3N2 strategy, and dashed lines to the 3N3 strategy.