The correct form of a computer system depends on the constraints and aim for which it was optimized. Computer architectures frequently trade off cost, standards memory capacity, latency and throughput. Sometimes other considerations, like as size, features, weight, , expandability reliability, and power consumption are factors as well.
The most general scheme carefully chooses the bottleneck that most reduces the computer's speed. In an ideal world, the cost is allocated proportionally to assure that the data rate is nearly the similar for all parts of the computer, having the most costly part being the slowest. It is how skillful commercial integrators optimize personal computers.