Even so, imho on a staging environment everything should be ready to deploy barring either functional acceptance or very, very unforeseen technical issues that

Even so, imho on a staging environment everything should be ready to deploy barring either functional acceptance or very, very unforeseen technical issues that didn't show up systems that mimic production just a tad less closely. Staging = "ready to roll", not "still needs testing to see if things break". Things shouldn't break on staging. Of course you can forgo manual QA if your automated testing is so perfect that staging is just a formality. I'm guessing ZenPayroll has that covered, given that they deploy to production "several times a week". So I assume "trying their best to break things" is just a flippant description of final acceptance, not QA testing.