Depends on the choreographer. Some rather subpar Chinese dancers have gotten choreo from Linichuk over the years, for example. And Zoueva & Shpilband are actively asking for novice and junior dancers. Some coaches and choreographers like to work with the newer talents, some not so much. As to who gets the best choreo from Marina, last year's best FD, IMO, went to Chock & Zuerlein, not their top 2 teams. So as I say, depends on the choreographer.
Aldridge & Eaton, who were also-rans last year, got great programs from Pasquale Camerlengo for this season, which was prior to them appearing at Junior Worlds at all.
In singles, Philip Mills, Ashley Wagner's choreographer, works with younger skaters, AFAIR.
And while he is not a big name, Rohene Ward, who works with Jason Brown, IMO is fabulous.
And if the person is willing to pay the big bucks, some big choreographers will take them on (just check out who choreographs for whom on ISU bios).
So having done well at Junior Worlds last year (6th), Han Yan should have had no problem this season and should have even less this coming season in finding a good choreographer and getting the great programs he deserves out of them, providing he or his federation is willing to pay the price for that.