To my extent, i found few studies reported that OCP is more equal to the electrochemical potential. Thereby, the potential exactly at OCP or below OCP is more thermodynamically stable (less tendency to take part in corrosion) whereas the potential above OCP is thermodynamically unstable and prone to corrosion (u can find RG community answered similarly) Also, it is given that above OCP condition, system isn't at state of equilibrium, where the results are non precise.

EIS is generally used to study the charge transfer characteristics between electrode and electrolyte. True behavior of electrode (charge acquisition and consumption from electrolyte) in term of corresponding resistances for example electrode-electrolyte resistance (lying in low frequency range) should be deduced only at equilibrium position (i.e. OCP). The EIS at potentials other than OCP would not reflect the original characteristics of electrode-electrolyte system.

EIS, at potentials other[1] than Vdc=OCP (a preferred polarization for icell=0), might include/add complex terms. These add-on terms might obscure[1] or coverup, the actual (super)capacitance (values' measurements) of the WE properties.

1. such uncommon polarizations drive to birthing high DC i_cell0, drives to conditions that are out from the thermodynamic equilibrium.

To my understanding, at OCP the reactions also happen at the same rate for the forward and backward reactions.

Suppose the measurement is started out of equilibrium, it means some electrochemical species will be kept consuming. The resultant impedance should have a contribution from the extrinsic factor; for instance, sample amount (can we supply those species with negligible change throughout the measurement duration?) and its mobility in the measuring matrix. The addition of complex phenomena will make the result more complex.

There might be some useful information that can be retrieved. But without a specific setup in mind, I do not see the reason to add complexity to the system.