It's definitely important, but we (Python shop) have "good" (85%) test coverage and we still see 500s in prod every day because of things a type checker could trivially catch. And this is just in the course of normal operation; this isn't even a migration. Having extensive experience with both Go and Python, I would conservatively estimate that Go requires ~30% fewer tests than untyped Python for the same confidence. That's more than 30% time savings; not only are you not writing 30% of the tests, but that's 30% fewer tests to have to maintain. Of course these aren't the only considerations--for certain tasks Python may be faster to develop with (although I think people forget about things like deployment, tooling, dependency management, performance requirements, etc when they make their estimations).
Yes, we all know the metric is easily gamed but no one at our org is trying to game the metric. We are paid to build a product, not to boost the metric.
I noticed something similar with Elixir with regards to the number of tests we needed thanks to the compiler, but it also has late binding (albeit it is statically typed). A "best of both worlds" exists out there
