What is the benefit of using a multiple bus architecture?

Compared to single-bus architecture, the using of multiple-bus architecture have a great advantage in speed and of course, will affect performance also. Instead of using single-bus architecture, it is more convenient to use multiple-bus architecture. Using multiple-bus architecture will make each device to connect to own bus, which means that each device will have its own bus. This way, it will be faster to transfer data of each devices, so the data transfer doesn't have to stuck like in the single-bus architecture where many devices are connected to a single-bus, that will eventually reach the capacity of the bus and thus will make the data "queue". Of course, it will cost more to have multiple bus, but the cost will not match the need of faster speed, compared to the one of that single-bus architecture.