When they revamped the starting zones back in the day it seems that all collection quests drop 100% of the time. I can at least confirm Northshire Abbey as I've just started a fresh team with no RAF. Folks in beta are reporting the collection quest drop rates to have been greatly increased [almost 100% drop rate], we can only hope this isn't "just a beta thing" and that it goes live with the expansion. Also have my fingers crossed that it finds it way into the revamped Azeroth, as well as Outland and Northrend, quest lines.