Recalling the definition of the Tafel exchange current density (forward direction) for the situation that one step is the rds in the analyzed potential region (Eq. 25a) one finds the notable relationship in Eq. 25b. Under the common assumption that the rds stays the same, one obtains Eq. 25c, which is again markedly different to Eq. 22. This difference arises from that the intermediate coverages through the formal potentials of the individual steps. Since the Tafel exchange current density is ubiquitous in the treatment of sluggish reactions such as the ORR/OER, using Eq. 22 to investigate the effect of changing binding energies carries several implicit assumptions, notable for the formal potentials of the individual steps. However, the formal potentials of the individual steps are generally not known, calculated, or even discussed.