Its a big YMMV on this one. I am 25K and on our last trip to Maui on a Comfort fare the 4 legs (YYC-YVR, YVR-OGG, OGG-YVR, YVR-YYC)
were all different. We did get our 4 free C Fare drinks. Ranged from FA already knowing we were on Comfort didnt have to ask, on the other 3 :
I asked and was given straightaway the FA knew about the promo on one. On the other 2 had to ask, and the FA just told her partner FA doling the drinks
and the 4th one neither FA knew & one went up & asked the SD. Obviously not something that is near the top of the list at FA training.