⌘-? is the best Mac keyboard shortcut.
Here’s why: It selects the search box in the Help menu, allowing you to filter on all menu items – including Recent Documents!
Some applications offer a quick open shortcut to access files you’ve recently opened but with this shortcut you can do this pretty much anywhere
I’ve known about the search field for a long time but it never clicked to use a keyboard shorcut and the “Open Recent...” submenu to this effect.
Now that I have ⌘-? fully internalised I’ve started using it for pretty much any menu item I don’t know the keyboard shortcut for.
I don’t know how I lived without it. Like an animal.