Depends imo.
If you are content with the team you have, save.
If you think you need to get Mei or someone else, pull.
I myself only pulled 2 rares from Kage. Got very happy with what I got, and now I'm saving up.
_Do not pull just for the sake of pulling_ Pull if you actually need anything. Seeing as you already have ninjas like Chojuro and Darui, you c*ready build strong teams.