I believe the change happened at the time AF reduced the number of FAs. I remember a time, not so long ago, when (nearly) every door had its dedicated crew member who had to check that their colleague standing across the aisle had correctly armed or disarmed the slides. Nowadays, each PNC looks after 2 doors and must therefore ''verifer la porte opposée'' as opposed to ensure their ''vis-à-vis'' has done their job properly.