I've never liked the conflating of target size and test time constraints. I very much agree that there's benefit to considering the pace of feedback and where

I've never liked the conflating of target size and test time constraints. I very much agree that there's benefit to considering the pace of feedback and where it falls in your workflow; immediate feedback is hugely valuable, but it can come from unit tests, other tests, or things which are not tests. Meanwhile, some tests of a single unit might have to take a long time. Exhaustive tests are rarely applicable, but when they are it's going to be for something small and it's likely to be slow to run. That should not be in your tightest loop, but it is probably clearer to evict it simply because it is slow, rather than because it is not a unit test for being slow.