Is there a general rule about accessing terminals after clearing customs? At some airports, after clearing customs, you're still in a secured area and can get back into the terminal, but at other airports, after clearing customs, the only exit is by going into the non-secured area.

For example, if you wanted to access a lounge (and did not have a connecting flight), could you go back through security and show them your boarding pass for the flight that just arrived to access the lounge? Is that a worldwide no-no, or is that a per-airport decision? (I'm guessing it's a worldwide no-no, from a security perspective, but thought I'd ask just in case.)