The chemical conditions of the interstellar medium (ISM) are regulated by a complex interplay of global and local dynamical processes, taking place within star forming clouds and the galactic potential as a whole. Processes such as spiral arm streaming motions, instabilities, and bar-driven mixing can have profound impacts on the (in)homogeneity of the ISM, and so quantifying the mixing scale over which metallicities are increasingly homogeneous gives us insight into the dominant processes in setting this homogeneity. Traditionally, metallicity variations have only been mapped radially in galaxies, but with high-resolution integral field spectroscopic observations as well as machine learning techniques, we can now map the azimuthal variation and the mixing scale of the ISM. I will present results applying this new technique to 19 galaxies observed with VLT/MUSE as part of the PHANGS-MUSE survey. I will link this mixing scale to various global galaxy parameters (e.g. stellar mass, star formation rate), and show the relative enhancement and suppression of metallicity in various environments (e.g. spiral arms, bars). These results indicate that the majority of these galaxies show strong, and significant azimuthal metallicity variation, and that the mixing scale indicates this homogeneity is primarily driven by global, rather than local processes (e.g. stellar feedback).