I think the surprise part in under-appreciated. The quicktest tests I write are frequently of the form “let’s spend 15 minutes and see what happens” kind of tes

I think the surprise part in under-appreciated. The quicktest tests I write are frequently of the form “let’s spend 15 minutes and see what happens” kind of tests - and I almost always find bugs that way. The return on investment is bonkers. I do think that immutable by default OCaml + good PBT tooling there helps a lot.