We're starting to see trigger warnings more and more now on books. A trigger warning essentially is a warning to potential readers that your book may contain graphic violence, rape, dog bites and other common tragedies that could have befallen your potential audience, thus triggering a painful response to your words. As far as I can tell, they act much like a rating on a movie might. Genre's used to be the go to subject when deciding on a book, but it looks as thought trigger warnings will be standard sooner then later.
I haven't employed these warnings on any of my books, but my trilogy; The Judas Syndrome, does have a number of traumatic scenes peppered throughout, so let me just run through a few of them while we're talking about it. The list would include suicide, depression, graphic violence, Christianity, guns, copious drug use, alcoholism, addiction, cruelty, heart break, isolation, desolation, amputation, sexual content, rape, child birth, life and death decisions, scavenging, hoarding, cold blooded murder, to name a few... oh, and the end of the world... there's that, so, if you have a fear of the apocalypse, you may want to avoid this series altogether. But if you like the content you just read, well, now you know!...
So I'm not sure if this better targets your intended audience or works to exclude potential readers. My guess is it will achieve both outcomes. But will it sell more books? Will it result in more positive reviews? I think I'll test it out on my trilogy in Amazon and see what effect it has on all of the above.