A wearable cardioverter defibrillator system, comprising: a support structure configured to be worn by an ambulatory patient; defibrillation electrodes (104, 108, 204, 208) which are coupled to an external defibrillator (100, 200) via electrode leads, wherein the defibrillator and the defibrillation electrodes (104, 108, 204, 206) are coupled to the support structure; an energy storage module (250, 350) configured to store an electrical charge; a discharge circuit coupled to the energy storage module; a transducer configured to render, from a sensed parameter that is an Electrocardiogram of the patient, a physiological input that includes ECG data of the patient; and a processor (230, 330, 930, 1030) configured to: perform a first-level analysis on a first portion of the physiological input to detect whether or not a possible shockable condition exists, the first portion including first ECG data (423_1) from a first time segment (T4_1), and perform, responsive to detecting by the first-level analysis that the possible shockable condition exists, a second-level analysis on a second portion of the physiological input to detect whether or not an actual shockable condition exists, the second portion including second ECG data (423_2) from a second time segment (T4-2), in which the second-level analysis is different from the first-level analysis, and performing the second-level analysis requires the processor to consume more energy than performing the first-level analysis if the first time segment had an equal duration with the second time segment, and control, responsive to thus detecting that the actual shockable condition exists, the discharge circuit to discharge the stored electrical charge through the patient so as to deliver a shock to the patient while the support structure is worn by the patient. a support structure configured to be worn by an ambulatory patient; defibrillation electrodes (104, 108, 204, 208) which are coupled to an external defibrillator (100, 200) via electrode leads, wherein the defibrillator and the defibrillation electrodes (104, 108, 204, 206) are coupled to the support structure; an energy storage module (250, 350) configured to store an electrical charge; a discharge circuit coupled to the energy storage module; a transducer configured to render, from a sensed parameter that is an Electrocardiogram of the patient, a physiological input that includes ECG data of the patient; and a processor (230, 330, 930, 1030) configured to: perform a first-level analysis on a first portion of the physiological input to detect whether or not a possible shockable condition exists, the first portion including first ECG data (423_1) from a first time segment (T4_1), and perform, responsive to detecting by the first-level analysis that the possible shockable condition exists, a second-level analysis on a second portion of the physiological input to detect whether or not an actual shockable condition exists, the second portion including second ECG data (423_2) from a second time segment (T4-2), in which the second-level analysis is different from the first-level analysis, and performing the second-level analysis requires the processor to consume more energy than performing the first-level analysis if the first time segment had an equal duration with the second time segment, and control, responsive to thus detecting that the actual shockable condition exists, the discharge circuit to discharge the stored electrical charge through the patient so as to deliver a shock to the patient while the support structure is worn by the patient. perform a first-level analysis on a first portion of the physiological input to detect whether or not a possible shockable condition exists, the first portion including first ECG data (423_1) from a first time segment (T4_1), and perform, responsive to detecting by the first-level analysis that the possible shockable condition exists, a second-level analysis on a second portion of the physiological input to detect whether or not an actual shockable condition exists, the second portion including second ECG data (423_2) from a second time segment (T4-2), in which the second-level analysis is different from the first-level analysis, and performing the second-level analysis requires the processor to consume more energy than performing the first-level analysis if the first time segment had an equal duration with the second time segment, and control, responsive to thus detecting that the actual shockable condition exists, the discharge circuit to discharge the stored electrical charge through the patient so as to deliver a shock to the patient while the support structure is worn by the patient.