Hellfire Necks, 1 at a time? Bulk? How many?

I'm now over the century mark for crafting Hellfire Necks and I have yet to get an Ancient with one of the core passives. I've gotten Ancients well rolled for crazy passives no one uses. I've gotten non-Ancients very well rolled. And I've gotten a ton of garbage.

When you craft your Hellfire necks, do you got one at a time? or do you craft bulk? If bulk, how many do you craft at once?

Today was "15" and "23" respectively. I think I would have cired a little more if I had done all 38 at once and got this mess.