Methods and apparatus for efficiently fulfilling product orders corresponding to different customers are described. An order processing system receives product orders from customers and efficiently groups multiple orders into sets of orders. A set of orders is assigned to a mobile sort wall, and a group of robotic carts is assigned to be used to collect products. The products corresponding to a set of orders are picked from racks and collected in the robotic carts. The mobile sort wall includes a plurality of different placement locations, e.g. bins. Each placement location is associated with one of the customer orders in the set of customer orders assigned to the mobile sort wall. A sorting kiosk including a scanner identifies a collected product, identifies a placement location, and the product is placed on the mobile sort wall. A loaded mobile sort wall is moved to a packaging area.