As CMOS technology scales to the 55 nm node, the concomitant thinning of the gate oxide has made Time-Dependent Dielectric Breakdown (TDDB) a key mechanism limiting chip reliability. The appropriate model for gate oxide TDDB lifetime projection—whether the E-model, 1/E-model, Power-law model, or $\sqrt{\mathrm{E}}$-model—remains a contentious issue, as extrapolations can differ by several orders of magnitude, thereby compromising the accuracy of lifetime assessments. This study systematically evaluates these four mainstream acceleration models using TDDB data from a 55nm process, comparing their goodness-of-fit across distinct stress regimes: a high-voltage region (2.7~2.85 V) and a low-voltage region (2.55~2.7 V). Our analysis reveals that while all models provide a reasonable fit to their respective data, their applicability is strongly dependent on the voltage regime. The E-model provides the optimal fit in the high-voltage region (R²=0.996 6), where the 1/E-model performs poorly (R²=0.994 5). In contrast, the 1/E-model demonstrates the highest fidelity in the low-voltage region (R²=0.991), where the E-model is least suitable (R²=0.987 9). The Power-law and $\sqrt{\mathrm{E}}$ models exhibit intermediate performance in both regimes. These findings indicate that no single model is universally applicable, instead, model selection must be based on the relationship between the stress conditions and the intended operating voltage. By contextualizing these results within the frameworks of percolation theory, the thermochemical model, and the anode hole injection model, this paper reveals the physical applicability boundaries of each model. Finally, leveraging the optimal model from the high-stress data, we extrapolate the characteristic lifetime of the 55 nm gate oxide at its nominal operating voltage. These research findings provide critical experimental evidence to guide model selection for TDDB lifetime assessment in advanced process nodes and hold significant practical value for robust reliability engineering.