New aisle designs have been proposed for unit-load warehouses recently in the literature. Most of these designs propose reduction in single-command expected travel distance considering flow from only one input/output (IO) point which is centrally located on the bottom of warehouse. Therefore, in this study we investigate the effects of varying number of IO points on both the layout and the distance. We use a warehouse network model to calculate expected single-command distance. We also use a Particle Swarm Optimization algorithm to search for the optimal values of the warehouse design variables. We showed that Leaf designs are robust for less than 7 input and output points on the bottom of the warehouse.