On October 31, 2026, a study published in Progress in Additive Manufacturing employed a stiffness-method rapid fatigue testing system to assess the competing effects of surface roughness and lack-of-fusion defects on the fatigue performance of 316L stainless steel specimens produced by laser powder bed fusion (PBF-LB/M) and electron beam powder bed fusion (PBF-EB/M). Validated across nine surface conditions, the method's fatigue limit results deviated by less than 2% from conventional staircase-method results while cutting testing time by more than 1,000 hours. Comparing polished and as-built specimens from both processes, the study found lack-of-fusion defects up to approximately 500 μm in PBF-EB/M versus 100–150 μm in PBF-LB/M, with surface roughness parameters of the electron beam specimens nearly double those of the laser process. By optimizing contour parameters (contour offset and number of contour layers), the fatigue limit of as-built specimens reached within 1.5% of polished specimens without post-processing, significantly reducing reliance on time-consuming and costly machining post-treatment. Insufficient fatigue performance is one of the core bottlenecks preventing metal additive manufacturing components from achieving widespread installation and application. Conventional fatigue testing requires numerous specimens, long lead times, and high costs. This study provides a low-cost, time-saving validation framework for fatigue performance assessment of additive manufacturing parts, while demonstrating that surface contour optimization strategies can effectively balance the negative effects of defects while preserving near-net-shape advantages—offering practical value for rapid certification in certification-sensitive sectors such as aerospace and medical. Value for powder buyers: (1) Reduced fatigue evaluation cost and turnaround will accelerate iterative validation of AM processes and powder grades, benefiting the pace of volume adoption for stainless steel powders such as 316L; (2) Control of surface quality and near-surface defects implies stricter requirements for batch consistency in powder oxygen content, sphericity, and particle size distribution—batch stability metrics should be included in procurement negotiations; (3) It is advisable to track expanded validation of rapid fatigue testing methods on additional grades such as titanium and aluminum alloys as a low-cost means of assessing powder batch quality.