For a turkey or something, cover with foil and let rest 15 minutes while you do the gravy. That lets the juices redistribute deeper into the meat, making it moister. You shouldn't lose that much heat over 15 minutes.
For a steak done from medium down, resting it is the difference between a bloody plate and a nice presentation as well as being more juicy and tender. Same thing with roasts.
As to the beef being overdone, always take it out 10 degrees lower than you want it to finish. The temperature will go up another 10 degrees from carry over cooking, sitting on the counter before it starts to go down again.
I'm new to this board and a new quilter so I can't help out much there, but been a chef for decades!
Watson