The "rule" also depends on what happens if you don't act. If you're in a large organization and CC'd by default and nothing bad really happens if you don't read your emails because your action is rarely needed, then sure.
If you're CC'd but the work won't be done if you don't read the email, because you are the one who will do the work, then it's not viable to skip CC's.
If you're CC'd but the work won't be done if you don't read the email, because you are the one who will do the work, then it's not viable to skip CC's.