De - icing / Snow / Change of weather
Yep, de-icing is an unpredictable thing with weather changes!
You could be de-iced for frost and be given a hold over time of five hours. BUT when it's / starts snowing, the fluid is being diluted and the hold-over time is reduced significantly to 15-20 mins! Thats why some smaller airports can't/won't de-ice in snow as they can't complete in time. as crew (if you are/were) you should have all the relevant information in the cockpit about holdover times according to the known fluid types used.
Otherwise the a.c should not be flown. Holdover times are guidelines only and are subject to change! I do hope training reflects this throughout the industriy!
Better safe than sorry, despite the thousands of extra pounds put on the bill!! Keep Safe!!!!
Take care
Deal