I do too but I'm not really a fan, yes it solves a problem cheaply but it's not a great solution, if you're unlucky with case design and fan placement it can be awkward to place and I've had mine slip once even though I didn't move the case, a lot better than nothing though.
I was starting to get black screens randomly, reseating the GPU solved it for a while but I haven't had it happen since getting the anti sag rod, the funny part is my current GPU isn't especially heavy (certainly less than the card it replaced) so I didn't think I'd need to support it but feel a little silly for not doing so sooner.
I'm ruling out new cases which don't offer an inbuilt anti-sag brackets as current GPU designs pretty much demand it.