I tried farming Ossuary and it was a chore
Someone pointed me towards Foothills, it's like a 50% speed improvement over ossuary because the flow is a lot better (which helps with intervention)... they are more likely to spawn near the checkpoint, you can reset in zone and when you tp to town you don't have to move and can reset right on the spot.
Sulphite scarabs are getting expensive right now
If level is not a problem, The Twilight Strand in act 6 might be better.