Trust me you'll come across examples like this one day if you make a concerted effort to automate a test for every story. It's a rough guess but I'd say I don't

Trust me you'll come across examples like this one day if you make a concerted effort to automate a test for every story. It's a rough guess but I'd say I don't automate 1 out of 20 stories - I'm not exactly blithely unaware of the benefits an automated test suite brings. Most of the examples that require "days" (or weeks) for the test and 5 minutes for the test would involve the building or amending an elaborate mock/stub. Some examples where this happens include rare interactions with weird hardware, odd legacy APIs that are scheduled to be replaced, race conditions and obscure edge cases with mocked services. I document all of these special cases and they should clearly remain special but I'm not going to blindly assume that automating the story will have a positive ROI.