I haven't, but I think that were trigger warnings are appropriate is in things that hurt a few people disproportionately. If something hurts everyone that reads it you shouldn't write it at all, and if it hurts no one more than it is worth it isn't a case for trigger warnings. But if it is something that needs to be said to many people, and there is a significant group (perhaps those that have had a certain experience) who would suffer a lot from reading it, then you put a trigger warning that would be recognized by that group at the top.
TLDR If most people never care about trigger warnings, then they might work as intended.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.