Seriously though, of course there's a lot of details here, but I think people tend to not really interenalize how much testing is about confidence, and things like incremental CI can really chew away at how big/small your test suite needs to be. There are some things that are just inherently slow, but I've seen a lot of test suites that are mostly rerunning tests that only use unchanged code for most of its runtime.
My glib assertion is that there is likely to be no test suite generated by 20 engineers that requires 30 shards that is impossible to chop up with incremental CI. And downstream of that, getting incremental CI would improve DX a lot, cuz I bet those 30 shards take a long time
