In Carl Flesch’s opinion, “the studies [by Ševčik] are the most important and time-saving material by which a modern violin technique can be achieved, but always provided that they are correctly applied.” He compared them to medicine which, “according to the amount taken can either kill or cure.” To prevent a “lethal” dose and to update the study material, editor Klaus Hertel, on the one hand, reduced the vast number of variants to what he considers necessary while, on the other hand, he has extended it by means of new exercises penned by himself.