Yeeeep it's occur after 3rd fight but in the 2nd fight even when 1 vs 2 Wuji still can't "win" since We know in DGSD with only very basic martial art skill (i.e Founder Long Fist) XF can "play around" with Xuannan and Xuanju..
As for Greats like Wuji I think almost Greats would win against Du Monk on 1 vs 1 fight since The Du Monk (individually) strength only around 1/3 of Greats
Wuji was winning against his two opponents in the second battle. The problem was that Yin Tianzheng's power was also diminishing. NB. that one of the Du monks was able to gain the upper hand against Yang Xiao and Yin Tianzheng combined shows just how strong they are - those two would almost certainly defeat either of the Xuanming elders individually.
the battle situation was clear for Kong Wen, Kong Zhi, Fan Yao, Wei Yixiao, and the other masters. They saw the mist coming out from the top of Yin Tianzheng’s head was getting thicker; on the other hand, the trunk, the branches and the needle-leaves of the big pine tree in which Du Jie was sitting were shaking constantly. From this fact, they knew the difference in level of power of the two monks, Du E and Du Jie. At this stage of the battle, Du Jie’s back was leaning against the tree to borrow its strength in blocking Zhang Wuji’s Jiu Yang Shen Gong. If Yin Tianzheng fell, the Ming Cult lost; but if Du Jie gave up first, then the Shaolin Pai was defeated.
In all fairness, Wuji wasn't dominating the monks to the same extent he did the Xuanming elders - but there's no doubt in my mind his ability was tested to a greater extent in those three fights than (certainly) his first encounter with the Xuanming two.
The 3 monks were really strong. They were all the next best fighters in Wulin after Z3F, ZWJ and the Yellow Dressed Lady. The worst monk would easily wreck any of the Xuanming elders, and probably beat both if he's careful.
ZWJ upgraded himself to an entire new level after the 3 fights, from the first one where he struggled and would lose eventually to the 3 monks, to the 2nd one where he was beating 2 monks by himself and would probably win if YX and YTZ would hold out a bit longer, and to the final one where he single-handedly fought the 3 monks to a draw.
In terms of martial arts level, that final battle is easily the best in the entire Condor trilogy. It's a well drawn-out fight with incredible stakes and both sides fought to the best of their ability. The internal level is obviously unmatched with ZWJ's 9Yang and the 3 monks' combined power. The external level is also unmatched with the telepathic formation, only to be bested by even more sophisticated combination of skills.
I would take ZWJ at this point against any Greats in the entire trilogy. And I think he's just getting into his prime. If he would go back to Wudang and consult with Z3F about 9Yin, it would be really scary.
- It's true Du Monk (indivually) stronger than Xuan Ming Elders (individually) but 1 Du Monk > 2 Xuan Ming Elders I think it's wrong even for Du E (the strongest among them) since only great level fighter like Wuji or Z3F could easily "destroy" both of Xuan Ming Elders
- It's also true that Wuji strength was very incredible even for JY canon which only few people could "overpowered" him but if he fought other Greats like GJ YG or HYS there is not only about "power" IMHO but also combine of skill experience and mentality
I wonder if ZWJ fight GJ YG, then he could imitate and learn quickly 18 dragon subduing palms and sad palms
I believe GJ YG is far better in terms of combat experience, but most of tje time we forget that we compare 20s year old ZWJ with aged GJ and YG
And also ZWJ (and also DGSD main characters) are wiitten later and give more story complexity and personality.
From the story point of view, If he could then the main character don't have any challenge and the story will be boring, ZSF and Xiao Zhao will have less role then
In all novel there are some inconsistency made to make it more complex and interesting.
There are a lot of inconsistency and weird things there if we want to check one by one:
1. ZWJ sneaking to guard the ZSF and 3rd uncle, no one recognize him as new person?
2. Persian people could go to small island in China easily, in 1300 M people will need years to go to china mainland
3. Xiao Feng can only do 18 dragon palms but so powerful.
4. XU Zhu can learn 18 dragon palms and simplified it easily, but how come he learn it without become XF disciples
5.
Your inconsistencies aren't that much of a problem:
1) Z3F and 3rd uncle had been in isolation for years and took little part in the daily activities of Wu Dang, so it is unlikely they would recognize every new face.
2) I assume you are talking about the 3 Persian Emissaries. They had been tracking Golden Flower Granny for years.
3) XF bad a strong background in Shaolin Martial Arts and a decade of actual combat experience, plus when cornered can even go berserk.
4) XZ was taught 18 DP by XF himself as XF wanted to simplify the art and had XZ help him with it, reducing the original 28 palms to 18 palms.