We found that a lattice vector of around 20 Å is the optimal choice combining high accuracy and relatively low costs (average RMSE of 7.0 meV/ Å and VASP runtime of 10.4 node hours). Utilizing a larger supercell of 24 Å yields a modestly reduced average RMSE (6.4 meV/ Å) but comes at more than 2 times increase in computational demands compared with 20 Å. In a smaller supercell (∼ 16 Å), the averaged RMSE increases marginally by 3.2 meV/ Å, but crucially, certain materials (BaO, GaP and GaAs) exhibit an over 30% RMSE increase. The individual RMSE and VASP runtime for each structure is presented in Supplementary Information Figure . This inconsistency, coupled with unconverged anharmonic properties, especially for BP and BaO as shown in Figure ), renders 16 Å an inadequate supercell lattice for reliable results. Thus, to strike a balance between accuracy and computational efficiency, a carefully benchmarked supercell size (lattice vectors 20±2 Å and a minimum of 150 atoms per supercell) has been adopted in our workflow. It should be noted that, for low-symmetry lattices that are particularly obtuse or acute, we perform a Lenstra-Lenstra-Lovasz lattice basis reduction to obtain a better set of orthogonal lattice vectors as the initial input structure.