I've seen evidence that reading a trigger warning and then consuming the content might be worse than just consuming the content without a trigger warning.
But is there any good reason to doubt that trigger warnings can be helpful in the obvious way: someone sees the trigger warning and makes an informed decision to avoid the content?
The nature of that setup makes it incredibly difficult to research. You'd have to answer a negative.
Of course, that won't stop people that are anti-trigger warnings from using the irrelevant research (they don't work if you don't heed them... duh) to push their agenda.
But is there any good reason to doubt that trigger warnings can be helpful in the obvious way: someone sees the trigger warning and makes an informed decision to avoid the content?