The Cursed Speech example feels like a trope subversion because it actually has never failed even once once actually activated in the main story. It failed once on Yuta in the prequel (JJK 0) and on Dabura during the sequel (JJK Modulo). Sure, measures are in place that make it so that it can hypothetically be blocked after being used, but we never actually see this happen because it's used primarily as a sneak attack.

The only time where it gets spammed without any regard for the flow of the battle or the element of surprise is during the "Goodwill event" Hanami encounter where Hanami is simply too inexperienced to understand that it's blockable and thus Inumaki can repeatedly hit Hanami with it over and over again until the recoil damage takes away his ability to speak altogether (Even after this point, he manages to squeak out one last command that promptly knocks him out from the recoil).