To make a trend, you need a wide sample, with no bias. Our sample is based on Forsaken, who were the best channelers of the AoL, and the heroes who were born to fight them. Rather selective, to make any conclusions.
It's based on every channeler stronger than Moiraine.
Or skilled. We don't know how he made his genetic alterations. In all likelihood they were made with machines or ter'angreal and his brain is to blame.
The major character reply is a bit of a cop out. I agree we have seen weak channelers with Talents, but not many. Berowin, Sumeko, Androl.
We have also seen that more than half of the women who have been dragged into making cuendillar are Yellow ajah, and that the key is strength in Earth. Thus a whole cluster of strength in a flow and two Talents. Very skewed and not coincidental. Egwene is strong in all the flows and the Power and has a whole host of Talents.
Once Nynaeve does start practicing, she improves. But not before. There's no default skill because she's so strong.
Her problem was her block and her total disinterest in anything that wasn't Healing. As early as TSR she was a direct match for Moghedien in combat. Alivia also only knows how to destroy things with the Power but she picks up things almost instantly. Her ability to see and apply herself with saidar worried Cadsuane, which means that it is not a common skill. And then, of course, Alivia's ability to equal Cyndane's skill with an angreal is proof that strength by its self is a type of skill that can overcome channeling adversity. Which is why Siuan Sanche and Moiraine have used angreal and sa'angreal to Heal in the past.
We've also seen Rand split his flows more than ten ways and weave incredibly complex weaves without training, before Asmodean taught him. Yet he couldn't do much else. There is innate ability there, albeit uncontrolled.
We have trends that confirm that, and exceptions that prevent us from making a rule. I don't want to make a rule. I'm perfectly happy with "tall people find it easier to change lightbulbs but there are some short people who are really good at it too."
I'm not familiar with that quote.
Fan of Lanfear