Dailey challenging missions / how much should they drop
Last couple of missions I've done (WT5 challenging) don't seem to be dropping a lot , did Lexington today and got 5 items (3 for Barrett ((none of the two I want but that's another story))
Loot during the run you mean? You are guaranteed 5 items (three from the boss two from the run). Anything more is RNG. On average I'd say you get 2/3 more items per run as drops from mobs, but RNG plays a big part, sometimes you get more, sometimes you get less.