Select applications are better suited for carts.
Carts are easier to implement in older shops with numerous building additions and floor elevations because a cart can provide the flexibility required to handle the constraints of an older shop.
Carts are also well suited to work in conjunction with a conveyor system. For example, many plants effectively use roller conveyor when processing components and then store the completed parts in a WIP area. An employee then uses a cart to pick and organize the necessary parts from the WIP and rolls the cart of parts to the assembler.