This thread did get me wondering.... so I took a look. This is reviewing last years Compendium (all three series) and last year's young guns (series 1 & 2, plus the 10 YG update).
First, I was surprised that 15 players had YGs, but NOT Compendium RCs:
223 Nathan Walker
461 Alex Nedeljkovic
462 Christian Jaros
473 Robbie Russo
475 Roland McKeown
488 Dylan Ferguson
489 Jack Rodewald
497 Andrew Mangiapane
499 Nick Merkley
513 Travis Boyd
514 Alexandar Georgiev
515 Andy Welinski
516 Colby Cave
517 David Kampf
520 Tanner Fritz
This left 26 players that got Compendium RCs, but NO Young Guns:
278 Nelson Nogier
285 Dan Renouf
290 Blake Coleman
291 T.J. Tynan
583 Chris DiDomenico
585 Garrett Mitchell
594 Jaycob Megna
596 Evan McEneny
833 Hunter Miska
836 Chase Balisy
848 Will O'Neill
851 Kurtis MacDermid
853 Justin Kloos
857 David Rittich
858 Ben Thomson
863 Justin Auger
867 Andrei Mironov
870 Andrew Crescenzi
875 Brady Austin
880 Viktor Antipin
887 Dakota Mermis
889 Ken Appleby
893 Tucker Poolman
894 Nick Ellis
896 Curtis Valk
897 Alex Lyon
Now... I'm using YGs as the set to compare to, as it's kind of the "standard" set - staple set, whatever you want to call it.
Of the players who had Compendium RCs, but no YG..... these ones also had no other cards last year:
833 Hunter Miska
836 Chase Balisy
848 Will O'Neill
853 Justin Kloos
858 Ben Thomson
863 Justin Auger
870 Andrew Crescenzi
875 Brady Austin
887 Dakota Mermis
889 Ken Appleby
894 Nick Ellis
896 Curtis Valk
897 Alex Lyon
(at least no other NHL cards. Some did have AHL cards).
So - There are certainly cases where UD has made Compendium RCs of guys, and that's it.