Abstract In a recent issue of this Journal, Cogliano (in ‘Marx’s equalized rate of exploitation’, Cambridge Journal of Economics, 2023, vol. 47, no. 1, 133–69) provided a theoretical basis of the hypothesis that the rates of exploitation are uniform across industries. In this paper, we compare the hypothesis and an alternative approach that assumes that the value creation per unit concrete labour is uniform. As neither approach considers skill differentials, we provide an extended framework that incorporates skills explicitly for the comparison. In addition, our framework considers the value creation of workers as a function of their skills and efforts of labour and, following Yoshihara (in ‘Wealth, exploitation and labor discipline in the contemporary capitalist economy’, Metroeconomica, 1998, vol. 49, no.1, 23–61), we define the ratio between effort and wage as labour discipline. Within this framework, we show the following. The equalisation of the rates of exploitation is eventually assuming that the ratios between the value creation and wage are equalised and it implies that high-skilled workers experience proportionately weaker labour discipline whereas low-skilled workers experience stronger labour discipline. On the other hand, the alternative approach that assumes the equalisation of the value creation per unit concrete labour implies that high-skilled workers work proportionately less intensively whereas low-skilled workers work proportionately more intensively.