Those limits are severely outdated. The 17 was before optimized algorithms. Fridrich did say that the limits are 10-12 seconds (look at her limits of speedcubing" page).
There's really no way to average more than 5 turns per second while during a CFOP solve. If you try to go faster, there's no way you can see the next pair in time.
So if you take that a CFOP solve is a little over 50 turns and a ZB solve is about 40, then 10 seconds/solve is really the limit. But ultimately, the most important factor is the cuber, not the system. Macky was heads and shoulders above everyone else for two years.