A few observations about trigger warnings that people don’t actually seem to understand:
If you post a graphic or disturbing picture on something other than tumblr (where Savior or something like it is not an option), it does NOT help to add a piece of text saying “trigger…
I find this sentence made by the OP sums up my feelings on the matter: “The goal is to convey the minimum amount of information necessary to let the reader make an informed choice whether to proceed, without getting so detailed that you actually manage to trigger them yourself.”
I think you might wanna use a vague term to suggest in what way your content may trigger negative emotion. Like “violence”, “mature theme”, “flashing lights”, “politics”… without going into the detail of what kind of violence/views/etc it is.