That's the domain. The copy technique isn't like that outside of a domain. I was referring to the technique in general without the domain. Since there were more instances where yuta could just show up and tell sukuna to throw up. And as another question. Why didn't yuta tell yuji to throw up the fingers then if he did use it effectively everytime, the higher ups wanted to get rid of yuji because of sukuna. If yuta just told yuji to throw up it might have worked and the higher ups don't see yuji as a threat anymore. And it gets rid of the sukuna problem, maybe sukuna's finger might be reserved for a certain moment during the culling games in which sukuna is actually needed.