I can't speak to all facilities, nor to all floors or the ER. But at one facility I have seen that 5 is the average med/surg pt load -- days or nights. There is the rare exception where you might get 6, but that's due to a number of factors and is definately the exception rather than the rule.
I did my preceptorship at another facility where I saw the night nurses come in to 7 or 8 patients from time to time. You can bet that scared me from applying there!! Dayshift usually consisted of 5 or 6 patients.