I have an anecdotal tale for CNK.
In the last period of sunspots I was sitting in a dxpedition pileup in the Extra portion of 20 meters. I couldn't hear the DX but the East Coast was loud. To amuse myself while I hoped conditions changed in my favor, I started looking up call signs. I found Extra class operators up and down the East coast but the 5th lookup was a General class.
hmmm.
A few more and another General class and later yet a third General.
Now, maybe they had a Extra class control operator sitting next to them. ?
It was one of the reefs that was activated last cycle. (Grin).