BOAC
Whenever you spray a fluid on your wing it is also an anti-icing. A de-icing process would be only possible with pure water only and this is not approved by any authority. Most pilots are forgetting that they have something on the wing, which may re-freeze, even no active precipitation is present. Very often the wing temperature is much lower than the OAT and well below freezing point. This can cause the fluid to freeze and you have no longer a clean wing.
It is a wrong assumption, I "made a de-icing only". This would only exist, when your temperatures (OAT and surface) are well above freezing point. Which in most cases never happen in winter. Several larger airlines made a wing temperature test programme a few years ago. I had been one of them being involved and I can guarantee you, that your wings stay much longer on cold temperatures you expect.
As a flight crew member you have to take the fact that whenever fluid is sprayed on your wings you better calculate hold-over-time.