Coin type hand exchange always happens every day on the exchange. You exchange BNB for USDT, the exchange will verify your request, that's when the coin transfer process occurs. Just like the BTC exchange process, every day there is demand and supply, in simpler terms to make it easier for you to understand this process. When you buy Bitcoin there is always someone selling it.
Bitcoin rotation will always be on its axis, the exchange process will continue as long as Bitcoin can still be exchanged.