If polarisation means: "any mechanical side-effect by which isolating barriers develop at the interface between electrode and electrolyte."
And if concentration polarisation is "changes in the electrolyte concentration due to the passage of current through the electrode/solution interface. Here polarization is understood as the shift of the Electrochemical potential difference across the cell from its equilibrium value. The cause of the changes in concentration (emergence of concentration gradients in the solution adjacent to the electrode surface) is the difference in the rate of electrochemical reaction at the electrode and the rate of ion migration in the solution from/to the surface."
Thus, should concentration polarisation cause a decrease in the performance/efficiency of a galvanic cell over time and would this be shown with a decrease of voltage/current through the cell? Or does voltage and current remain the same throughout a galvanic cell reaction?