Actually, it's not a myth. I asked Brandon last August and he confirmed RJ used 21 levels for women.

He said "few" women were stronger than Nynaeve. He could not answer specific questions because "the list" is with documents regarding the bell curve, the total # of channelers and how many can be of which strength etc. and he had not more than looked at that stuff (he gave the impression it's not a topic he's too interested in). He did not even remember (at the time) if the Forsaken were included or if only third Age women were distributed on 21 levels (he seemed under the impression Nynaeve was on the top level).


To write he rather had used RJ's big "quick guides", two documents listing not only the level for every woman and man, but all sort of details like weaves he has established in the series channeller X know, and which he had determined she doesn't know (to avoid contitnuity errors - a sister with poor healing skills suddenly having average or better etc.), the stuff not listed on there he still had room to make up as he went along. Also the deference relationships already established in the series are extended in that guide (for people who had not interacted before, RJ used the level numbers to determine it). For younger channellers, the QG also stated their current level and the level they would reach and stuff like that.

RJ kept that stuff current to write, for more details he had to go to Maria and his characters' notes. The "list", bell curve etc. were to create characters and keep it consistent with his strength distribution, the "guides" were the continuity tools when writing.

Another thing Brandon confirmed in that brief discussion while he was setting up his laptop to show the few people who remained behind after the signing some WoK concept art is that RJ indeed did not compare strength between men and women (for the usual reasons RJ told us, Brandon confirmed). He kept two separate lists and two separate "quick guides". He did not remember how many levels the men had. The male document was less for hierarchy (like the AS notes) and more for continuity - who knows what etc.