I thought it was the norm everywhere to have flaps fully retracted for de-icing?
Yes, but we had an incident in OSL 3 weeks ago. Aircraft landed late at night on a contaminated runway. Crew left the flaps down for inspection. Contracted engineer arrives later to do daily check, by this time flaps are covered in snow. So he leaves them where they are after inspecting and finding nothing in cavities.
Next morning new crew arrives and asks for deicing on the gate. This is not allowed in OSL, you must taxy to the deice pans. Crew would not taxy with flap extended so aircraft towed to deice pan (which is a long way) for deicing.
I never found out why they would not taxy out, there is a statement to allow this in their FCOM.
Personally in this case I do deicing with the flaps where they are, then retract the flaps for anticing, but it is a bit of a foggy area.
I do not believe that there is any point in leaving the flaps down for inspection on an A320. The chance of slush going up there is very remote. I have tried to get this instigated, but Airbus says NO.