This study addresses order-picking routing optimization in a wide aisle of a mechanized warehouse. Efficiencies of the three popular heuristic policies (return, traversal, and Z-pick) are compared for different pick densities. A modified Z-pick policy with a flexible string length is proposed to increase its efficiency and accommodate lift-truck movement. The simulation-based results show that all three policies are not significantly different in the pick density region of 10–15 percent. The traversal policy performs better at pick densities below the region of indifference, while the return policy outperforms the others at higher pick densities. However, the Z-pick provides a viable universal alternative across all tested pick densities.