Those principles of Naturalness as postulated by Mayerthaler (1981) claim to make predtictions about the direction of language change possible. It is true that the majority of morphological changes can be accounted for by these principles. However, systematic violations of these rules can be found in of all things, some of most frequent, elementary verbs such as HAVE, BE, BECOME, COME, GO, GIVE, TAKE, etc. Their irregularities cannot be accounted for solely - as Naturalness Theory would have it - by conflicts between phonological and morphological Naturalness. Rather, they have been systematically built up through other efficient strategies. This "regularity of irregularity" is the focus of this paper, which demonstrates several particularly well-beaten paths to irregularization through contrastive diachronic investigations of frequent verbs in different Germanic languages. lrregularity, a term laden with negative connotations, is substituted by the term differentiation, which names the actual function directly. Because differentiation typically correlates with word brevity, this constellation should be considered an ideal compromise between hearer and speaker interests. A further question to be addressed is which individual categories are expressed through irregularization. It is concluded that this process is guided by token frequency and degree of relevance.