Would not go as far as to say "delivered" in 48 hours. Shipping can be relatively slow during those promotional days and the app even shows delay warnings on the cart screen / checkout.
True, but remember "slow" means something quite different in China where same/next day delivery is very often expected in top tier big cities. So 3-5 days delivery is definitely considered slow, and during these crazy period you may see the glacier speed of one week delivery time :)