Could you add a shortcut/command to select all keyframes in a comp? Not sure if already it exists. I couldn't find a way to do that. CTRL+ALT+A only select the keyframes visible in the timeline.
This is how it is supposed to work. Anything more than that will require a script. Check AEScripts.com where you can also find scripts to shift keys in time and mangle them in other ways, which I suspect is the real question behind your question. Perhaps you care to explain?!
You don't have to install any scripts. You can just select all layers, hit UU to reveal all changed properties and select the keyframes. See?! This isn't something that would necessarily require yet another way of doing it.
Yes I know, but if you have a bunch of layers you have to scroll down to select all the keyframes. I think it's missing a simple command and CTRL+ALT+A is a bit pointless in my opinion.