Practical limit of rock mineral wool products

Has anyone experimented with extremely thick (say 1m+) layers of rock mineral wool products (Knauf Acoustic batt for instance), to determine its efficacy in absorbing very low frequency (say <50Hz) sound waves. The Porous Absorber Calculators seems to suggest that there is a limit (+/- 600mm) beyond which adding more depth does not improve its ability to absorb low frequencies.