In C# I'm generally using Verify for these happyflow tests - So instead of explitly testing every individual property, you just do Verify(state); and compare the entire state against a json saved state.

A little bit for the same reason of "testing fatigue" - having to manually rewrite assertions of a lot of tests is getting annoying. With that approach you just do a merge compare between results, accept them, and you're done

Well... This sounds like optimizing tests for coverage. Which is not a novel idea, but certainly not the worst.

This is a decent idea for certain cases, but you’ll almost always have a better time if you use property based testing, in which case you can handle all negative cases with only a few such tests.