Precisely because of his high demands, he would keep you working on the same thing over and over until you'd nailed it, to his satisfaction.
If you failed to meet his expectations, he would rather stop filming than make do.
There was only 100 percent with him, never 99 percent.
Furthermore, they were such deep movies that required deep acting, highlighting the actors' acting skills.
It could be said that having Deng Xu to coach them, to run them through their scenes, and to direct for them was more than worth it.
There was no other director better qualified than Deng Xu within the country.
That's not to say that other directors were worse than Deng Xu.
Directors more well-known and with more accolades than Deng Xu existed, but not many were as "nitpicky" as Deng Xu, who insisted on getting his perfection.
All in all, Deng Xu was the best candidate.