No, it isn't. If you measure 7 point and they give the same answer, you know for sure that every point between those 7 is also the same. Anything between point 1 and 2 will be the same. Or 3 and 4. That's 1/4 of the surface. How likely is it that points to the left and points below are different? I would say zero to none. In any case, the method I just used, working backwards from calibration numbers, shows that the flow rate was 4.1 m/s, just as he said. That could not be a coincidence. It is not likely that it was 4.1 m/s at all 7 points, yet if he had measured 2 more they might have been 5.0 and 3.2 (averaging 4.1). That is implausible.
I have just measured the flow and it varies considerably. It is turbulent. (The 60 cm tube approaches laminar flow) That may mean well-mixed. That does not mean homogenous.
Here they are again: 25 cm tube (top), and 60 cm tube (bottom), same fan as Mizuno, 65 mm ID.
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