Existing and future large-scale spectroscopic surveys feed a demand for fast and efficient tools for the determination of fundamental stellar parameters. Such tools should not only comprise customized solutions for one particular survey or instrument, but, in order to enable cross-survey comparability, be capable of dealing with spectra from a variety of spectrographs, resolutions, and wavelength coverages. To meet these ambitious specifications, we developed ATHOS (A Tool for HOmogenizing Stellar parameters), an analysis tool that adopts easy-to-use, computationally inexpensive analytical relations tying flux ratios of designated wavelength regions in optical spectra to the stellar parameters effective temperature, iron abundance, and surface gravity. I will outline our fundamentally new approach and its empirical derivation from a stellar benchmark sample. ATHOS' extraordinary performance in terms of accuracy, precision, and speed will be demonstrated on a selection of spectroscopic surveys, such as the Gaia-ESO survey. Finally, I will use the horizontal branch star HD~20 as a showcase to prove that our new parametrization method can compete even with the more resource-demanding analysis techniques tailored to the in-depth study of much smaller stellar samples.