Tightness of triply eclipsing triple systems (P_out/P_in) as a function of the system compactness. λ Tau (orange circle, Ebbighausen & Struve 1956) is not triply eclipsing, but it is otherwise such a noteworthy benchmark system that we include it for reference. The most compact triple, TIC 290061484, is the leftmost system in the plot. The empirical and theoretical lower limits for dynamical stability are marked with solid and dashed horizontal lines, respectively. A speculative upper boundary is marked with the sloped red dot-dashed line.