The ZIgbee battery-powered TRV's are actuators, they listen for incoming Zigbee commands. To save the battery, their radio is turned off most of the time, but the firmware is made to turn it on periodically, typically once for a short time period every second.
Many Zigbee blinds controllers and Zigbee locks have a similar battery-saving behaviour, that's why these devices do not react to the open/close commands immediately, but after some delay.
No, the TRV instantly sends updates to the hub when an attribute changes (the measured temperature as an example).
The TRV automatically reports back the heating setpoint to the hub immediately after accepting the command. There is no need for additional 'poll' commands.
This is a custom driver feature, that you can turn off
As stated in the preference description, one possible reason for the polling could be to produce a better looking graphs :
It may be a good idea this polling option to default to 'disabled', typically it is not needed.
