Surely, if one operates in third world countries, the answer comes naturally.
Operating in Europe only, one might say depressurizing sys A is exaggerated... but I'm sure that if we had access to the whole record of pushback incidents/accidents, one would change his mind...
- taking France, then, as a third world country
, or, to be fair, any country where the national language is not English, it is ALWAYS worth being careful with pushback crew. In my most memorable case, Montpellier:-
"Hello bonjour [matelot] (note the linguistic flair) - your checks please"
" OK - 'eer we go"
Park brake off just in time before nosewheel was snapped off
Followed by "arretez arretez" (impressed?)
I remember also that DanAir had a nosewheel driven back into the fuselage on a 146 when pushback in AMS was started before the brakes were called off.