OK. Let us do the math.
4'x4'x7' = 112 CF
CFM is Cubic feet per minute. So it would require a 112 CFM of exhaust one minute to refresh a 4'x4'x7' tent. There is no such thing, but a 190 even if only operating at 50% or 95CFM would exhaust and refresh this size tent in approx. 80 seconds.
So; you can disagree; However, the math proves you wrong.
Another note. Any fan size will do. It is only a matter of how fast, or how long a duration is necessary to recycle the tent completely.
This can easily be done with the fan I posted. Good day now, lw