So the way an analog signal (user's speech X) is handled, is that it is sampled at 8000 bits / sec.
The high-speed C-channel has 128 kilo bits/sec of capacity.
X only transmits at 64kbps
A transmits at 64 kbps too.
However, if the switch 1 only "listens" to X for some time constant, and then switches to A, wouldn't it make the speech of X seem slury/ with pauses? Let's imagine user X is talking continuously for 5 minutes, if switch 1 is switching between X and A, then there will be short pauses in what user X is saying, isn't it?
So why is circuit switching even considered as a viable option in telephone communication? It's not.