Lol yeah I actually wrote it- I mistook you for c2g- she has pics of her stock in the beginning of this thread where she includes her mirepoix and bouquet in it. Sorry
And no, there's no benefit to it. You actually burn out the flavor compounds and make a bland, foggy stock. It may even get blander. The moment your veggies have given their all they should be removed- and they give it all after about 2 hours after cut at 1" size. The only thing you'll get is mushy veg that floats around in their and slowly breaks apart, causing the cloudiness.
Ideally the stock Should be strained and chilled down to fridge temp as fast as possible at around the 5 hour mark.
Edit- it is totally advisable to cool your heavy stocks like beef or veal overnight- beef bones/knuckles take a long time to give out their collagen and the tomato paste you often rub on the bones needs extra time to flavor the stock