There are many factors, that may affect the solution resistance, e.g. the position of the reference electrode to the working electrode. If the RE is placed away, then the Rs will increase. Also, the shape and geometry of the working electrode will affect the equipotential lines, which affects the Rs. i.e. the roughness of the surface might slightly affects.

It you are using a three electrodes configuration you should not observe significant variation. The Rs valute in this case depends only on the resistance of the solution layer

Any low conductivity layer present at the electrode surface will add extra resistance, depending on if your high frequency limit. Typical cases are carbon steel and stainless steel, this last showing apparent higher electrolyte resistance due to Cr2O3.

Thanks a lot for your explanations...