China's government policy and central bank tightly control the exchange rate and only allow it to fluctuate within certain predetermined bands. "An official re

China's government policy and central bank tightly control the exchange rate and only allow it to fluctuate within certain predetermined bands. "An official re-adjustment of the mid-point rate for the trading band is announced by the country's Foreign Exchange Trading Center at 9:15 a.m. each day, Shanghai time." https://www.fxcm.com/uk/insights/how-does-china-control-exchange-rates/ https://www.fxcm.com/uk/insights/how-does-china-control-exch... So each day the government says what the currency should be and gives traders very little wiggle room. As for the first question should they or shouldn't they do it, I don't know.