Well, for one, it depended entirely on the service branch and what country the pilots belonged to. VMF-241 (Blacksheep) pilots, during the Boyington days at least, did not have their own airplane, it was just whatever was closest.
Also, for getting into the planes, it would have depended on the plane. The F4U you got in on the right, whereas the Hellcat you could get in on both sides. There are a lot of different variables.