why RX_CALLBACK_SIZE is defined as 8 in dsps-v_5.150.2 example?

Hi Dialog support team,

In dsps-v_5.150.2 example, macro named as RX_CALLBACK_SIZE was defined as 8. It means after every 8 byte of data received from UART , UART RX ISR loop(void uart_sps_rcv_data_avail_isr(void)) is stopping to receive bytes and calling the callback function below.
My understanding is correct or not? If my understanding is correct, when more than 8bytes are going to be received at a time,then it will miss the remaining bytes or not. Please give some explanation for this?

if(rcv_bytes)
{
void (*rx_callback) (uint8_t, uint32_t);

// Reset RX parameters
uart_sps_env.rx.bufptr = NULL;

// Retrieve callback pointer
rx_callback = uart_sps_env.rx.callback;

if(rx_callback != NULL)
{
// Clear callback pointer
uart_sps_env.rx.callback = NULL;

// Call handler
rx_callback(SPI_STATUS_OK, rcv_bytes);
}
else
{
ASSERT_ERR(0);
}
}