I find this one comes up a lot for me. After you have created your first comp in a project, AE remembers the comp length so any new comps are of the same length. So you drop your next footage layer into this new comp...but the comp isn't long enough. It was the right length for the last footage you worked with, but too short for the new one. Is there a quick and easy shortcut (maybe even a script) to "extend comp to match layer" so that the comp then becomes the same length as the footage layer?