Class C Design Question

Quick question regarding class C device.

I am trying to understand why, in class C, the device switches from RX2, then to RX1, then back to RX2. Why does it not just open RX2 window after transmit and keep it open until next xmit?

As seen in timinig diagram of class C here:

It switches to RX1 only after sending an uplink, I believe because sending an uplink turns the device into a Class-A device flow temporarily.

Note that this also enables the Network Server to use a different data-rate and frequency for the downlink than configured for RX2.