Some departments have part of their mission to train and develop physician scientists. They probably try to take 2-3 residents a year who have real potential and drive to groom for an academic career. If you’re one of them it will most definitely help. If you’re not one of them, I think it’s a waste of energy to do half-assed research solely to buff your CV. The departments know most of their graduates will go into clinical practice. Anesthesia is not derm or ortho, it is not necessary to have research to match even into a top 3 program, whatever they may be. As Facted states above, do research if you like it. Otherwise do other stuff with your time. For most people, spending extra time studying for their steps will be a better use of their time.