Surface density profiles of models with different Ṁ_int at distinct evolutionary stages. Panel a shows the initial configuration for all models, while panel b presents their structure after the first TI and the subsequent diffusion of the resulting density bumps. Panel c compares the surface density of MREF and M3 at the start of their respective second TI cycle, and panel d shows the structure of both models after they have become quiescent again (similar to panel b). In all cases, the TI phase persists until enough mass has been accreted so that the surface density does not exceed Σ_cut.