Context <p>The multiscale modeling of charge carrier dynamics in amorphous organic semiconductors is fundamentally challenged by the inherent sampling limitations of atomistic morphologies. This work provides a critical investigation into how finite-size artifacts in molecular dynamics (MD) supercells introduce spurious anisotropy in carrier transport, even in systems comprising as many as 2000 molecules. I demonstrate that off-lattice kinetic Monte Carlo (kMC) simulations based on Marcus transfer theory often yield directionally biased mobility values that lack physical consistency under low-field strengths due to these scale-dependent constraints. To address these limitations, I propose an on-lattice kMC framework that reconstructs the local molecular environment while preserving the essential statistical features of the disordered system. Compared to conventional off-lattice approaches, the presented method offers a more stable and representative description of the field-dependent mobility across varying MD cell sizes. This study highlights the necessity of accounting for finite-size effects in multiscale workflows and establishes lattice-based reconstruction as a practical alternative for achieving statistically reliable transport simulations.</p> Methods <p>Amorphous morphologies of 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) were generated for system sizes ranging from 250 to 2000 molecules using Desmond MD simulations with the OPLS4 force field. Marcus transfer parameters were calculated via density functional theory (DFT) using the Amsterdam Density Functional (ADF) package at the PW91/TZ2P level and Gaussian software at the B3LYP/6-311G** level. Charge carrier transport was then simulated via in-house kMC codes to investigate the resulting carrier dynamics. The proposed on-lattice framework was compared with the conventional off-lattice approach in terms of transport isotropy and sampling efficiency.</p>