In my view no wake is just that no wake.
As others have said, every boat has its own "no wake" speed. I have traveled behind Paul on Jackie J V, a 560DB. At idle, he is probably at about 7 or 8 knots and slides through the water with no wake. For me to keep up at that speed in my 330DA, I am at about 1200rpm or more, and definitely throwing a wake that would NOT qualify as no wake. So if its truly a no wake zone, I need to let him get ahead and try to catch up later when we can get on plane (and that is tough to do, since his top speed is about the same as mine, probably more).