Abstract: In embodiments, a wearable medical system (“WMS”) implements a wearable cardioverter defibrillator (“WCD”) that senses and samples a patient's ECG signals. In a regular mode, the WMS produces a first set of ECG values, which can be the minimum needed for a WCD operation. In a second or rich mode of operation, the WMS produces a second set of ECG values, more numerous than the first set. The rich mode can be implemented by sampling the ECG signal faster, and/or not ignoring ECG signals in channels that are ignored in the regular mode, and/or by having more ECG sensing electrodes than the minimum needed for the WCD operation. The WMS stores the first set and the second set, and uses either one to determine whether defibrillation is needed. In addition, it communicates them to another device. In embodiments, support structures for a WMS have multiple ECG electrodes for just sensing.