Seriously I know Jill was in 5, but not counting DLC, she wasn't a main playable character. And Revelations had both Jill and Chris has main playable characters right? I really no nothing about Revelations since I can't play it :v
From my experience with the game, you play with Jill more than you do any of the other characters in Revelations.
Honestly, I could do without seeing Chris or Jill for a while though. Both of them have been used quite frequently as of late.