Advance Keys

In my opinion, you pick a cam that's right for what you want from the engine and matching the other components. Then degreeing the cam would be for verifying the cam is in where it should be in relation to the crankshaft, regardless of accuracy of machining on the block, cam, or timing set. Degreeing allows the builder to verify it's in where it's supposed to be. You can advance or retard the cam's intake centerline by adjusting the keyways, but IMO that means you probably have the wrong cam. It's way too general to say "they all run better with a couple degrees advance". They don't. I haven't had to use keyways to "fix" cam timing since I stopped using MP cams. Many of those ones DO want to be run advanced even when you can get them into the recommended ICL. Many also look like they've been ground by a blind monkey having a bad Friday.
The short answer - if you want low end torque - use a cam that closes the intake valve early enough to develop good cylinder pressure at low rpms. Then degree it to make sure the ICL is where it's supposed to be. If you run the right cam, from a decent manufacturer, you won't need keyways unless the timing set or crank were poorly manifactured. And if you buy a decent timing set (Summit billet is one of my favorites for quality, adjustability, and value) then you can use the timing set to correct any issues degreeing finds.