Active galactic nuclei (AGN) are known to be variable in many respects and across many timescales. In order to probe the geometry of AGN and better understand their overall variability it is important to disentangle spectral components corresponding to the different structures surrounding the central supermassive black hole (SMBH). In the X-ray band, the main contributors to spectral variability are the coronal continuum, variations in the line-of-sight absorption, and reprocessing in the accretion disk, in the broad-line region and in the torus. Because of their different spatial scales, they vary and correlate with the coronal continuum on different timescales. I will present the principles of self-consistent multi-epoch broadband spectral modeling that helps to constrain spectral parameters better than the simpler and commonly used analysis of multiple epochs using a single-epoch model in each one of them. This approach can maximize the return from repeated observations of bright local AGN with eROSITA and further our understanding of the AGN torus in particular.