It also depends on whether it is overclocked or not, small overclock is enough, big overclock is small.
Also look at the type of CPU, intel is usually enough, AMD overclocking a little small.
Of course it has to do with the heatsink, the side blowing is enough, the downward pressure is a little small, if the heatsink design is not good, even smaller.
So don't detect the number of fan revolutions, mainly to see the CPU temperature, the fan as long as the temperature increases when accelerating, the temperature decreases when decelerating, will not stop spinning on the line.