I know it's a big mystery to some people.. it may depend on two things. First, the setter's skill and confidence (not in a day but in years, esp. the setters who play in different leagues and work with different trainers (specialists), they are more experienced and brave ), but Russian setters don't have such an advantage bcz they don't work with strong trainers in Russia. FE, so far Italian Sergio was the only one who forced Russian setters to play with MBs. Koroleva isn't the only MB in Russia who can score, there are some..
If I remember correctly from volleyballmagazine some US coaches are serving as Russian players advisors on that matter, to a select few but I can't remember if the coaches go to Russia or the players go to the US for the meeting. But that was back in 2016 I don't know if it still stands.