It's also not all about channeling either... Nynaeve had zero skills (acquired) and was blocked, yet Siuan deemed her too old and too strong to be a novice. Of course, this wasn't normal, but still...
The main factor the AS are looking at in recruits is strength of character/personality. They don't give the shawl to women who have not yet been shaped into proper AS, who will behave like AS. They also have to reach the minimal level for Acceptance, and likely that for the shawl later (and the whole set of weaves used in the test), but in those two cases it's a matter of gaining on your potential more than having learned fast. To AS, strength in the OP is stupidly equated to leadership qualities, so they tend to see stronger recruit as being stronger persons naturally, and it part it's true because they treat them as if they were stronger and promised to greater things, while weaker ones are treated as weaker person. Want it or not, this sinks in... which explains the subdued nature of a Daigian, for instance.
The thing is, we can't really know if weaker women progress in their weaving slower than strong women, for AS do not deal with their recruits equally... they won't make weaker women progress very fast, and they probably also believe that stronger women must work harder and progress faster because they're in more danger....
AS are so biased, and also don't use angreal to help the weaker women to have enough strength to learn and make work some weaves (I seriously doubt they like WO teach weaves that a woman isn't able to make work), we can't draw much conclusions.
We'd have to compare to how things go among the Aiel, but except to tell us that all women were trained to their fullest no matter their strength, RJ has not left us information.
Personally I tend to think stronger women usually progress faster because, without angreal, they have sooner access to larger quantities of saidar to weave. But since we've seen weak women who remain very good weaver, I suspect it's not a matter of talent, skill, ability and with an angreal to use a weak woman could train as fast as a much stronger one.
The point I was trying to make is that Training and Learning the OP are not the same thing. We know that Moiraine came to the White Tower with a stellar education due to her position in the royal family of Cairhien and this played a role in her quickly moving from Novice to Accepted, meanwhile Siuan came in practically without an education, but still managed to progress quickly because she was something of an OP savant, thus her focus was on mundane knowledge while Moiraine's focus as a Novice was on the Power.
They both gained strength rapidly enough to be strong enough to meet the minimum requirements for the Ring and the Shawl, but neither was at their full potential (I would guess they were around a 18/19 when they reached the Shawl).
Daigian, was almost certainly at her full potential after nearly 50 years, but to your point she likely wasn't really focussed on by her strength obsessed Aes Sedai teachers and thus would have struggled with nearly every weave.
On the other hand there are women like Silviana who spent enough time in training that she must have been at her full potential when she achieved the Shawl and possibly even when she became Accepted. Her issues seemed to be rooted in the OP part of the training, similar to Nynaeve's issues.