How fast does the bus need to be to avoid becoming the bottleneck of the system?

Question

Computers

For example, if the DMA controller has 4 channels. The controller is capable of asking for a 16-bit word every 50 ns. The response to the request takes the same time. Then how fast should the bus be so as not to become the bottleneck of the system?

Answer 1

It must be absent or lattency must be 0