I work on a step down cardiovascular surgical unit....staffing on days is typically 2:1 or 3:1, depending on acuity, evenings is typically 4:1 (that can flex up to 5:1, but that doesn't happen to often, thank goodness!), and nights is typically 5:1 (and can flex up to 6:1). It's seems like a great ratio for the acuity of patients we get nowadays!