This work is a numerical and experimental investigation of the effect of the use of a metallic absorption layer on the laser-based measurements of the thermal conductivity of dielectric, semiconductor, and highly-conductive materials. The specific experimental studies, which were carried out on silicon dioxide samples, were used to validate the numerical approach and to support the findings of this investigation. The numerical and supporting experimental results reveal the presence of behaviors associated with thermally thin and thermally thick absorption layers, depending on the ratio between the thickness of the absorption layer and the heat penetration depth. It is concluded that the TTR method performs optimally when the thickness of the metalization layer falls in the transition range between the identified thermally thin and thermally thick layers.