I'm in agreement with Jim that 501+ per hour is most likely exaggerated, or more likely the question was misread as to training session. If your training session is 3 hours, I could see 500+ for the session, but not per hour.
I answered in the 51-70/hour range, but I didn't count our warmups in the count. If I count that, we do probably 150% to 200% more...around 175-200 or so...but that's in 1.5 hours.
That's my 2 cents per hour.