Glad that you worked this out, but I think there are two worries here: HTTP interference (which actually shouldn't be an issue, given that we're using HTTPS) and some kind of systemic emergent limitation of Bagheera.

Without having load-tested the Bagheera cluster, I would rather this number be as low as it can be and still converge on deleting all the documents that need to be deleted, rather than as large as it can be to fit within HTTP limitations. The failure mode is worse if we hit some internal timeout in Bagheera because it has to schedule 20 deletions, and fails every time, rather than making two requests with 10.

In theory this could be 2 or 3 and still work. I'd settle for 10. Thoughts?