I've got my Atlas set up to just drop Shaped Burial Chamber maps at T8 and T9, and I've got it going pretty well sustainability wise. Here's what I've learned.
I ran through about 150 chaos worth of Fortune Favors the Bold.
It's not worth it. I wasn't getting increased map drops. I got some coins, and actually managed to drop 2 exalt shards, but I just rolled through the chaos with very little return.
Chisels are worthless. I've had more success with map drops since I ran out of chisels. Now, it's probably an aberration since every guide ever says to chisel your maps, but for me they just don't seem to do anything at all...
Almost every time I have packsize over 20% I drop another Shaped Burial Chamber. Fortune Favors the Bold didn't seem to help map drops at all, nor did quantity seem to matter. Also, Fortune Favors the Bold is pretty dangerous... I spawned Abaxoth twice and died once to him... What a pain.
Sextants are a HUGE help, particularly the stupid barrel one that spawns the slugs (seems like it doubles the mobs on a map). I ran yesterday with two sextants from level 88 to 89 and increased my overall map pool from 10 to close to 20. This was a lot better than Fortune Favors the Bold.
Prophecies help, but they are extremely random... I've been really enjoying the new recipes that allow you to gain 5 prophecies or to seal all prophecies. Sometimes you can string 4 prophecies in a map. Sometimes you get stuck with some terrible ones.
Also its really hard for me to keep track of all these things. I'd roll a really good map only to find that I didn't put new sextants on, or I'd keep running without filling up my prophesies. It feels a lot like Legacy league where I kept forgetting to put in new league stones...