The technique is very reliable, as the reconstruction of the magnetic field maps with different algorithms yield almost identical results, even with poorly sampled data sets. It has however been shown, from both numerical simulations and observations, that the magnetic field strength and complexity is underestimated if no linear polarization spectra is available from observations. Since linear polarization signatures are weaker compared circular polarization their detections are not as reliable, particularly for cool stars. With more modern spectropolarimeters such as the recently installed SPIRou at CFHT and CRIRES+, currently in the process of installation, at the Very Large Telescope (Chile) the sensitivity to linear polarization will increase, allowing for more detailed studies of cool stars in the future.