I got the golden snuff box on a weeknight, somewhere in the 7 to 9 PM range (within the first ten kills of the match). Emerald Chimera is thought to drop frequently around 3:45 PM EST in the afternoon, but this is only a theory .
Now that Talbot's Fal is more balanced, the "Marlowe villain loadout" seems like a worthwhile goal: you get a Para-9, an M9, and a free Sugar Buddy booster. It's extra money for free, assuming your buddy is a decent player.
I also feel the frustration in this thread. You can get 10-20+ kills per hardcore match but the only drops will be repeat Just Cash or repeat Silver Snuff Boxes at certain times of day. This supports the notion that the rare treasures are possibly timed instead of map-based.
(For previous poster, Doughnut Drake's hematite skull bead is glitched. It will not drop on either hard or crushing, as it is supposed to do.)
Here's a question for everyone: has anyone earned a rare treasure in overtime? (I have, once.)