Scatter plot of the feedback timescale as a function of the surface density contrast between the CO emission peaks and the galactic average (ε_CO; see text). Spiral arms are represented in orange, inter-arm regions in blue. The solid lines represent the linear models fitted to the data in logarithmic space for each of the two environments. The red line marks the correlation obtained by Kim et al. (2022) for full galaxies, on a wider sample of 54 galaxies (including the 22 analysed in this work). The dashed lines represent the 1σ confidence intervals of the linear model for spiral arms (orange) and inter-arm regions (blue).