I have always accepted without much skepticism the idea that applying meat juices to roasts makes them more moist. In particular basting joints is commonly advocated as a way to "preserve moisture". It seems that is less certain that I had assumed, for example this answer doubts it, with a comment stating that it is "50s food mythology". There is this attempt (non paywalled text here) at a "scientific" analysis, and with an N of three detects no difference in moisture levels.
I have never been into basting meat, mostly because it is too much like hard work, but also because I imagine the juices are in contact with the meat for such a short time that it seems unlikely to make a large difference. What I have always been into is methods that ensure some contact between meat juices and the meat I want to make juicy. This came up in a recent question I asked where I stated that "I always cook [birds] breast down, so the breast is sitting in the juices and so does not dry out". An answer stated "sitting in the juices won't really make the breast juicier".
This is quite surprising to me, and goes to the heart of what I thought I knew about cooking meat. One principle that seems linked to this is covering meat with fat, for example recommendations to cook Beef Brisket "fat side up" and placing bacon on game birds breast. My butcher sells their pheasant with the bacon in place, indicating that this is common.
The closest I have come to a scientific analysis has been experimenting cooking muntjac haunchs to get them acceptable for guests including a pregnant woman. I have tried at multiple temperatures from 150 - 240 °C and it is difficult to get it sufficiently cooked to not have red juices and the meat to be juicy cooking it without covering. If I wrap the haunch in pig skin it will be juicy every time no matter the temperature. I have done this while entertaining a few times now and it is a reliable, relatively cheap and interesting meal to serve guests who are not familiar to game.
As I understand it the counter argument is that what you are mostly doing is cooling the meat so slowing it down. This can give the impression that you are preserving moisture as you are preventing overcooking. Under this hypothesis one would expect to get the same effect by reducing the temperature of the oven.
If we define the objective as widening the window where meat is cooked enough to kill any germs and does not have a taste/texture that is described as "dry" do any of these techniques for applying meat juices to roasts (or any others) work better than just reducing the temperature of the oven?
- Placing a bit of fatty meat/skin on top of the joint
- Wrapping the meat in fatty meat/skin
- Ensuring the bit susceptible to drying (ie. breast) is in contact with the juices