Segmented fetch for visualisations other than discover

Title pretty much says it all. I have many large indices (thousands of indices with millions of documents each, billions in total), and occasionally I want to get some fact about the whole lot. Currently the best way to do this is using Discover.

It looks like Discover working for me in this case, where other visualisations timeout, is down to 'courier:maxSegmentCount' - am I reading right that this only affects Discover? Is there a way to generalise, or an equivalent for other vizes?