I’ve used Paula Deen’s foolproof roast method and it’s been perfect every time with any roast we have cooked, including tenderloin. No thermometer required.
Since we’ve made it this way, any time I talk about trying another method or recipe, everyone objects. It turns out moist and just a perfect medium rare. The one change we are all ok with is using Montreal steak seasoning if I don’t want to work too hard.