Thermal degradation of polymers has traditionally been studied using experimental Thermogravimetric Analysis (TGA) techniques to estimate degradation rates and, consequently, the degradation times. These experiments are highly sensitive to the specific polymer, its composition, and the experimental conditions. Consequently, degradation rates are often not comparable across different polymers and may lack reproducibility even for the same polymer under similar conditions. Furthermore, approximate rate rules derived from these experiments are frequently used minimum homolytic bond dissociation energy/free-energy (BDE/BDFE) in the polymer repeat unit as a surrogate for stability using the ALFABET package, which was trained on much more diverse range of structures compared with the baseline model. While the BDE/BDFE model outperformed the alkane-trained model on small molecule predictions, the alkane model matched or surpassed it in polymer stability predictions. This suggests that polymer kinetics are more sensitive to detailed degradation pathways and relative errors than small molecule kinetics, which can often be approximated as first-order homolytic bond dissociation. This result highlights a potential disconnect between traditional small molecule metrics and polymer behavior that we explore in detail.