Timescales associated to the various processes at play in the Galactic transport of CR protons are plotted as a function of kinetic energy E_k. The diffusion τ_diff and convection τ_conv timescales are respectively featured by the long dashed and short dashed-dotted black curves. They are combined into the disc residence time τ_disc plotted as the solid black line. The energy loss and diffusive reacceleration timescales correspond to the solid purple and orange curves. The red solid line features the combined timescale τ_eff as given in Eq. (D.3).