The man she loves is lying there dying on her bed, of course she makes the attempt. Her Talent is too weak to be effective, he was still going to die. There is no evidence that an angreal would boost her ability. Moiraine had a very strong Talent for Healing and was significantly weaker than Egwene so it's possible that she could do more with one, but Egwene can obviously put many times the strength necessary to make the weaves function against this problem and still could barely achieve anything. Her level of Talent was clearly maxed out by this effort.

Yet Sorilea is stronger than Androl. The obvious answer is she doesn't have a strong enough Talent with Gateways at her strength. Like we saw with Siuan, give her a strength boost and she could make the weave function, but only to the extent her Talent allowed.

As for abstract Talents ... We keep hearing that there are degrees of ability. Elaida has a weak Talent, Egwene is a strong Dreamer,, and will "outstrip the WO someday", Gitara "Had the Foreteling very powerfully" ... This is all over the text. Clearly there are ways to judge the strength of a Talent as well. Granted these are relatively passive Talents and have no effect of weaves since they are not reliant on them, but it's obvious that not all Dreamers or Foretellers are not created equal.

You don't want to believe that characters can say things in the books and be wrong, despite misconception being thematic throughout the series. Do the math, everyone (except the FS) talks about Strength for gateways for the first few months they are around. Then suddenly we start seeing Androl who throws that argument out the window since its obvious that what he does (according to Taim) should be impossible. Eventually AS will start to notice that there are women who are making gateways that are disproportionate to their Strength, Give the Brown and the White some time to investigate and I would bet they realize many nuances. It likely won't be as dramatic as Androl, who is clearly an outlier, but, for argument sake, when Beonin can make a gateway nearly the size of what Egwene can and Lelaine can't match that folks will start to wonder why. Medani is another potential candidate for strong Traveling Talent IMO. She manages a decent size gateway and splits her flows to carry Verins corpse, something we know to be difficult. So she's either a lot stronger than we think she is or she is gifted in Traveling, also note Medani is similar to Androl in her love of travel... Nice little hint for us.

As for how common it is ... All you have to do is look at how many people can actually Travel. We know it is a Talent, which means in order to do it you must possess some level of the Talent or now matter how strong you were you wouldn't be able to make the weaves work to any meaningful effect, Nynaeve can't make Cuendillar, Semihage being poor at Weather etc... Therefore it follows that the Talent is somewhat common to the Channeling community.

Ultimately I think this boils down to this.

1. I think Androl's ability makes judging someone's OP Strength from gateway size invalid. Just as it would be foolish to measure Berowin's strength based on who she can shield. In fact I tend to believe you cannot accurately judge OP Strength based on any individual effect. There are simply too many variables involved. Yes strength is part of this, but you can't back into someone's strength based on a single effect that obviously Talent plays a huge role in.

2. I think the Talent defines the maximum extent a Channeler can effect something. It is very possible that a weak Channeler with a massive Talent such as Androl could create an even larger gateway if you handed him an angreal ... I would say that is a case where the Talent is beyond his natural Stength and therefore he can continue to add strength and get a larger effect. But on the flip side of that Flinn has to put far more strength into his much smaller gateway, and likely would not be able to make a significantly larger one even with an angreal, his level of Talent is restricting the size of the gateway. It's like a flashlight, the bulb is the Talent and the battery is strength. As the battery power fades the light grows dimmer until there is not enough power to make the thing work. But no matter how powerful the battery the bulb will never be brighter than its maximum output and it might even blow if you put too much power behind it. Finn has a 10 watt bulb with a strong battery and Androl has a 100 watt bulb with a weak battery. Flinn is clearly perturbed by this lack as he must knew that the amount OP he has to use to make a gateway is more than other Asha'man ... It obviously bugs him to not understand why.

Circles and mixed circles are too difficult to judge since we don't have enough information on how Talent is affected in these circumstances. The BotW effect certainly seems indicative that there may well be a huge increase in effectiveness when Linked, as that circle managed an effect well beyond what the Bowl was designed for and it was by no means a massively strong circle (by AoL standards).