Honestly no harm in asking simple questions. I m not Airbus 320 so don't know but previous Airbus I flew I was told if the APU bleed switch was left on beyond the limitation it would lead to pressurization problems (this is Airbus 310 I am referring to, and there were cases many many years ago in our line operations)
Compared to few Boeing a/c now I guess there's no harm as a pilot error wont lead to pressurization issues (for eg b777) the system design already switches to engine bleed above the limitation altitude.
while non standard practices are never encouraged but there is no harm in knowing the consequences of a pilot mistake with information that is validated correctly from simulator/books/other pilots/engineering etc.
Sorry have not answered your question.